Added overlay to OSystem interface; implemented overlay in SDL backend (all other backends, including SDL_gl, still need to implement this!); changed NewGUI to make use of the overlay; added Cmd-Q as a shortcut for Quit on MacOS X

svn-id: r4971

11 files changed, 522 insertions, 394 deletions

diff --git a/backends/sdl/sdl-common.cpp b/backends/sdl/sdl-common.cpp
index bdedb8ed1a..3c1fd3a151 100644
--- a/backends/sdl/sdl-common.cpp
+++ b/backends/sdl/sdl-common.cpp
@@ -81,7 +81,7 @@ void OSystem_SDL_Common::init_size(uint w, uint h) {
 	_cur_pal = (SDL_Color*)calloc(sizeof(SDL_Color), 256);
 
 	dirty_rect_list = (SDL_Rect*)calloc(NUM_DIRTY_RECT, sizeof(SDL_Rect));
-	_mouse_backup = (byte*)malloc(MAX_MOUSE_W * MAX_MOUSE_H * MAX_SCALING);
+	_mouse_backup = (byte*)malloc(MAX_MOUSE_W * MAX_MOUSE_H * MAX_SCALING * 2);
 	dirty_checksums = (uint32*)calloc(CKSUM_NUM*2, sizeof(uint32));
 
 	load_gfx_mode();
@@ -424,12 +424,15 @@ bool OSystem_SDL_Common::poll_event(Event *event) {
 		switch(ev.type) {
 		case SDL_KEYDOWN: {
 				byte b = 0;
-				if (ev.key.keysym.mod & KMOD_SHIFT) b |= KBD_SHIFT;
-				if (ev.key.keysym.mod & KMOD_CTRL) b |= KBD_CTRL;
-				if (ev.key.keysym.mod & KMOD_ALT) b |= KBD_ALT;
+				if (ev.key.keysym.mod & KMOD_SHIFT)
+					b |= KBD_SHIFT;
+				if (ev.key.keysym.mod & KMOD_CTRL)
+					b |= KBD_CTRL;
+				if (ev.key.keysym.mod & KMOD_ALT)
+					b |= KBD_ALT;
 				event->kbd.flags = b;
 
-				/* internal keypress? */				
+				// Alt-Return toggles full screen mode				
 				if (b == KBD_ALT && ev.key.keysym.sym==SDLK_RETURN) {
 					property(PROP_TOGGLE_FULLSCREEN, NULL);
 					break;
@@ -439,6 +442,7 @@ bool OSystem_SDL_Common::poll_event(Event *event) {
 					quit();
 					break;
 				}
+				// Ctr-Alt-1 till Ctrl-Alt-7 will change the GFX mode
 				if (b == (KBD_CTRL|KBD_ALT) && 
 				    (ev.key.keysym.sym>='1') && (ev.key.keysym.sym<='7')) {
 					Property prop;
@@ -446,20 +450,28 @@ bool OSystem_SDL_Common::poll_event(Event *event) {
 					property(PROP_SET_GFX_MODE, &prop);
 					break;
 				}
-				#ifdef QTOPIA
+#ifdef MACOSX
+				// quit on Cmd-Q on Mac
+				if ((ev.key.keysym.mod & KMOD_META) && ev.key.keysym.sym=='q') {
+					quit();
+					break;
+				}
+#endif
+
+#ifdef QTOPIA
 				// quit on fn+backspace on zaurus
-				if (ev.key.keysym.sym==127) {
+				if (ev.key.keysym.sym == 127) {
 					quit();
 					break;
 				}
 				// map menu key (f11) to f5 (scumm menu)
-				if (ev.key.keysym.sym==292) {
+				if (ev.key.keysym.sym == 292) {
 					event->event_code = EVENT_KEYDOWN;
 					event->kbd.keycode = 286;
 					event->kbd.ascii = mapKey(286, ev.key.keysym.mod);
 				}
 				// map center (space) to tab (default action )
-				// i wanted to map the calendar button but the calendar comes up
+				// I wanted to map the calendar button but the calendar comes up
 				//
 				else if (ev.key.keysym.sym==32) {
 					event->event_code = EVENT_KEYDOWN;
@@ -480,12 +492,11 @@ bool OSystem_SDL_Common::poll_event(Event *event) {
 					event->kbd.keycode = ev.key.keysym.sym;
 					event->kbd.ascii = mapKey(ev.key.keysym.sym, ev.key.keysym.mod);
 				}
-				#endif
-				#ifndef QTOPIA
+#else
 				event->event_code = EVENT_KEYDOWN;
 				event->kbd.keycode = ev.key.keysym.sym;
 				event->kbd.ascii = mapKey(ev.key.keysym.sym, ev.key.keysym.mod);
-				#endif
+#endif
 				
 				switch(ev.key.keysym.sym) {
 					case SDLK_LEFT:
@@ -718,8 +729,6 @@ void OSystem_SDL_Common::draw_mouse() {
 	if (SDL_LockSurface(sdl_screen) == -1)
 		error("SDL_LockSurface failed: %s.\n", SDL_GetError());
 
-	add_dirty_rect(x, y, w, h);
-
 	dst = (byte *)sdl_screen->pixels + y * SCREEN_WIDTH + x;
 	while (h > 0) {
 		int width = w;
@@ -739,6 +748,9 @@ void OSystem_SDL_Common::draw_mouse() {
 
 	SDL_UnlockSurface(sdl_screen);
 	
+	// Mark as dirty
+	add_dirty_rect(x, y, w, h);
+
 	// Finally, set the flag to indicate the mouse has been drawn
 	_mouse_drawn = true;
 }
diff --git a/backends/sdl/sdl-common.h b/backends/sdl/sdl-common.h
index bd2410ab2a..3da878a6e6 100644
--- a/backends/sdl/sdl-common.h
+++ b/backends/sdl/sdl-common.h
@@ -106,17 +106,12 @@ public:
 	static OSystem *create(int gfx_mode, bool full_screen);
 
 protected:
-	typedef void TwoXSaiProc(uint8 *srcPtr, uint32 srcPitch, uint8 *deltaPtr,
-								uint8 *dstPtr, uint32 dstPitch, int width, int height);
 
 	SDL_Surface *sdl_screen;      // unseen game screen
-	SDL_Surface *sdl_tmpscreen;   // temporary screen (for 2xsai)
 	SDL_CD *cdrom;
 
 	enum {
 		DF_WANT_RECT_OPTIM			= 1 << 0,
-		DF_REAL_8BIT				= 1 << 1,
-		DF_SEPARATE_TEMPSCREEN		= 1 << 2,
 		DF_UPDATE_EXPAND_1_PIXEL	= 1 << 3
 	};
 
@@ -166,7 +161,6 @@ protected:
 	int16 _mouse_hotspot_y;
 	int _current_shake_pos;
 	int _new_shake_pos;
-	TwoXSaiProc *_sai_func;
 	SDL_Color *_cur_pal;
 
 	uint _palette_changed_first, _palette_changed_last;
@@ -180,8 +174,8 @@ protected:
 	
 	void add_dirty_rect(int x, int y, int w, int h);
 
-	void draw_mouse();
-	void undraw_mouse();
+	virtual void draw_mouse();
+	virtual void undraw_mouse();
 
 	virtual void load_gfx_mode() = 0;
 	virtual void unload_gfx_mode() = 0;
diff --git a/backends/sdl/sdl.cpp b/backends/sdl/sdl.cpp
index eeea78fbee..ef8633bea4 100644
--- a/backends/sdl/sdl.cpp
+++ b/backends/sdl/sdl.cpp
@@ -24,6 +24,10 @@
 #include "common/scaler.h"
 #include "common/engine.h"	// Only #included for error() and warning()
 
+// FIXME - this macro assumes that we use 565 mode. But what if we are in 555 mode?
+#define RGB_TO_16(r,g,b)	((((r>>3)&0x1F) << 11) | (((g>>2)&0x3F) << 5) | ((b>>3)&0x1F))
+//#define RGB_TO_16(r,g,b)	((((r>>3)&0x1F) << 10) | (((g>>3)&0x1F) << 5) | ((b>>3)&0x1F))
+
 
 class OSystem_SDL_Normal : public OSystem_SDL_Common {
 public:
@@ -36,12 +40,31 @@ public:
 	// Set a parameter
 	uint32 property(int param, Property *value);
 
+	// Overlay
+	virtual void show_overlay();
+	virtual void hide_overlay();
+	virtual void clear_overlay();
+	virtual void grab_overlay(int16 *buf, int pitch);
+	virtual void copy_rect_overlay(const int16 *buf, int pitch, int x, int y, int w, int h);
+
 protected:
+	typedef void ScalerProc(uint8 *srcPtr, uint32 srcPitch, uint8 *deltaPtr,
+								uint8 *dstPtr, uint32 dstPitch, int width, int height);
+
+	SDL_Surface *sdl_tmpscreen;   // temporary screen (for scalers/overlay)
 	SDL_Surface *sdl_hwscreen;    // hardware screen
+	bool _overlay_visible;
 
-	void load_gfx_mode();
-	void unload_gfx_mode();
+	ScalerProc *_scaler_proc;
+
+	virtual void draw_mouse();
+	virtual void undraw_mouse();
+
+	virtual void load_gfx_mode();
+	virtual void unload_gfx_mode();
 	void hotswap_gfx_mode();
+	
+	int TMP_SCREEN_WIDTH;
 };
 
 OSystem_SDL_Common *OSystem_SDL_Common::create() {
@@ -52,7 +75,7 @@ void OSystem_SDL_Normal::set_palette(const byte *colors, uint start, uint num) {
 	const byte *b = colors;
 	uint i;
 	SDL_Color *base = _cur_pal + start;
-	for(i=0;i!=num;i++) {
+	for(i = 0; i < num; i++) {
 		base[i].r = b[0];
 		base[i].g = b[1];
 		base[i].b = b[2];
@@ -66,34 +89,151 @@ void OSystem_SDL_Normal::set_palette(const byte *colors, uint start, uint num) {
 		_palette_changed_last = start + num;
 }
 
+void OSystem_SDL_Normal::draw_mouse() {
+	if (!_overlay_visible) {
+		OSystem_SDL_Common::draw_mouse();
+	}
+
+
+	if (_mouse_drawn || !_mouse_visible)
+		return;
+
+	int x = _mouse_cur_state.x - _mouse_hotspot_x;
+	int y = _mouse_cur_state.y - _mouse_hotspot_y;
+	int w = _mouse_cur_state.w;
+	int h = _mouse_cur_state.h;
+	byte color;
+	byte *src = _mouse_data;		// Image representing the mouse
+	uint16 *bak = (uint16*)_mouse_backup;	// Surface used to backup the area obscured by the mouse
+	uint16 *dst;					// Surface we are drawing into
+
+	// clip the mouse rect, and addjust the src pointer accordingly
+	if (x < 0) {
+		w += x;
+		src -= x;
+		x = 0;
+	}
+	if (y < 0) {
+		h += y;
+		src -= y * _mouse_cur_state.w;
+		y = 0;
+	}
+	if (w > SCREEN_WIDTH - x)
+		w = SCREEN_WIDTH - x;
+	if (h > SCREEN_HEIGHT - y)
+		h = SCREEN_HEIGHT - y;
+
+	// Adjust for tmp_screen offset
+	x++;
+	y++;
+
+	// Store the bounding box so that undraw mouse can restore the area the
+	// mouse currently covers to its original content.
+	_mouse_old_state.x = x;
+	_mouse_old_state.y = y;
+	_mouse_old_state.w = w;
+	_mouse_old_state.h = h;
+
+	// Quick check to see if anything has to be drawn at all
+	if (w <= 0 || h <= 0)
+		return;
+
+	// Draw the mouse cursor; backup the covered area in "bak"
+
+	if (SDL_LockSurface(sdl_tmpscreen) == -1)
+		error("SDL_LockSurface failed: %s.\n", SDL_GetError());
+
+	dst = (uint16 *)sdl_tmpscreen->pixels + y * TMP_SCREEN_WIDTH + x;
+	while (h > 0) {
+		int width = w;
+		while (width > 0) {
+			*bak++ = *dst;
+			color = *src++;
+			if (color != 0xFF)	// 0xFF = transparent, don't draw
+				*dst = RGB_TO_16(_cur_pal[color].r, _cur_pal[color].g, _cur_pal[color].b);
+			dst++;
+			width--;
+		}
+		src += _mouse_cur_state.w - w;
+		bak += MAX_MOUSE_W - w;
+		dst += TMP_SCREEN_WIDTH - w;
+		h--;
+	}
+
+	SDL_UnlockSurface(sdl_tmpscreen);
+	
+	// Mark as dirty
+	add_dirty_rect(x, y, w, h);
+
+	// Finally, set the flag to indicate the mouse has been drawn
+	_mouse_drawn = true;
+}
+
+void OSystem_SDL_Normal::undraw_mouse() {
+	if (!_overlay_visible) {
+		OSystem_SDL_Common::undraw_mouse();
+	}
+
+
+	if (!_mouse_drawn)
+		return;
+	_mouse_drawn = false;
+
+	uint16 *dst, *bak = (uint16 *)_mouse_backup;
+	const int old_mouse_x = _mouse_old_state.x;
+	const int old_mouse_y = _mouse_old_state.y;
+	const int old_mouse_w = _mouse_old_state.w;
+	const int old_mouse_h = _mouse_old_state.h;
+	int x,y;
+
+	if (SDL_LockSurface(sdl_tmpscreen) == -1)
+		error("SDL_LockSurface failed: %s.\n", SDL_GetError());
+
+	// No need to do clipping here, since draw_mouse() did that already
+
+	dst = (uint16 *)sdl_tmpscreen->pixels + old_mouse_y * TMP_SCREEN_WIDTH + old_mouse_x;
+	for (y = 0; y < old_mouse_h; ++y, bak += MAX_MOUSE_W, dst += TMP_SCREEN_WIDTH) {
+		for (x = 0; x < old_mouse_w; ++x) {
+			dst[x] = bak[x];
+		}
+	}
+
+	add_dirty_rect(old_mouse_x, old_mouse_y, old_mouse_w, old_mouse_h);
+
+	SDL_UnlockSurface(sdl_tmpscreen);
+}
+
 void OSystem_SDL_Normal::load_gfx_mode() {
 	force_full = true;
 	scaling = 1;
 	_mode_flags = 0;
+	_overlay_visible = false;
 
-	_sai_func = NULL;
+	_scaler_proc = NULL;
 	sdl_tmpscreen = NULL;
+	TMP_SCREEN_WIDTH = (SCREEN_WIDTH + 3);
 	
 	switch(_mode) {
 	case GFX_2XSAI:
 		scaling = 2;
-		_sai_func = _2xSaI;
+		_scaler_proc = _2xSaI;
 		break;
 	case GFX_SUPER2XSAI:
 		scaling = 2;
-		_sai_func = Super2xSaI;
+		_scaler_proc = Super2xSaI;
 		break;
 	case GFX_SUPEREAGLE:
 		scaling = 2;
-		_sai_func = SuperEagle;
+		_scaler_proc = SuperEagle;
 		break;
 	case GFX_ADVMAME2X:
 		scaling = 2;
-		_sai_func = AdvMame2x;
+		_scaler_proc = AdvMame2x;
 		break;
 
 	case GFX_DOUBLESIZE:
 		scaling = 2;
+		_scaler_proc = Normal2x;
 		break;
 
 	case GFX_TRIPLESIZE:
@@ -102,11 +242,13 @@ void OSystem_SDL_Normal::load_gfx_mode() {
 			goto normal_mode;
 		}
 		scaling = 3;
+		_scaler_proc = Normal3x;
 		break;
 
 	case GFX_NORMAL:
 normal_mode:;
 		scaling = 1;
+		_scaler_proc = Normal1x;
 		break;
 	}
 
@@ -114,55 +256,30 @@ normal_mode:;
 	if (sdl_screen == NULL)
 		error("sdl_screen failed failed");
 
-	if (_sai_func) {
-		uint16 *tmp_screen = (uint16*)calloc((SCREEN_WIDTH+3)*(SCREEN_HEIGHT+3),sizeof(uint16));
-		_mode_flags = DF_WANT_RECT_OPTIM | DF_SEPARATE_TEMPSCREEN | DF_UPDATE_EXPAND_1_PIXEL;
-
-		sdl_hwscreen = SDL_SetVideoMode(SCREEN_WIDTH * scaling, SCREEN_HEIGHT * scaling, 16, 
-			_full_screen ? (SDL_FULLSCREEN|SDL_SWSURFACE) : SDL_SWSURFACE
-		);
-		if (sdl_hwscreen == NULL)
-			error("sdl_hwscreen failed");
-		
-		/* Need some extra bytes around when using 2XSAI */
-		if (sdl_hwscreen->format->Rmask == 0x7C00)	// HACK HACK HACK
-			Init_2xSaI(555);
-		else
-			Init_2xSaI(565);
-		sdl_tmpscreen = SDL_CreateRGBSurfaceFrom(tmp_screen,
-							SCREEN_WIDTH + 3, SCREEN_HEIGHT + 3, 16, (SCREEN_WIDTH + 3)*2,
-							sdl_hwscreen->format->Rmask,
-							sdl_hwscreen->format->Gmask,
-							sdl_hwscreen->format->Bmask,
-							sdl_hwscreen->format->Amask);
-
-		if (sdl_tmpscreen == NULL)
-			error("sdl_tmpscreen failed");
-		
-	} else {
-		switch(scaling) {
-		case 3:
-			_sai_func = Normal3x;
-			break;
-		case 2:
-			_sai_func = Normal2x;
-			break;
-		case 1:
-			_sai_func = Normal1x;
-			break;
-		}
-
-		_mode_flags = DF_WANT_RECT_OPTIM | DF_REAL_8BIT;
-
-		sdl_hwscreen = SDL_SetVideoMode(SCREEN_WIDTH * scaling, SCREEN_HEIGHT * scaling, 8, 
-			_full_screen ? (SDL_FULLSCREEN|SDL_SWSURFACE) : SDL_SWSURFACE
-		);
-		if (sdl_hwscreen == NULL)
-			error("sdl_hwscreen failed");
-		
-		sdl_tmpscreen = sdl_screen;
-	}
+	uint16 *tmp_screen = (uint16*)calloc(TMP_SCREEN_WIDTH*(SCREEN_HEIGHT+3),sizeof(uint16));
+	_mode_flags = DF_WANT_RECT_OPTIM | DF_UPDATE_EXPAND_1_PIXEL;
 
+	sdl_hwscreen = SDL_SetVideoMode(SCREEN_WIDTH * scaling, SCREEN_HEIGHT * scaling, 16, 
+		_full_screen ? (SDL_FULLSCREEN|SDL_SWSURFACE) : SDL_SWSURFACE
+	);
+	if (sdl_hwscreen == NULL)
+		error("sdl_hwscreen failed");
+	
+	/* Need some extra bytes around when using 2XSAI */
+	if (sdl_hwscreen->format->Rmask == 0x7C00)	// HACK HACK HACK
+		Init_2xSaI(555);
+	else
+		Init_2xSaI(565);
+	sdl_tmpscreen = SDL_CreateRGBSurfaceFrom(tmp_screen,
+						TMP_SCREEN_WIDTH, SCREEN_HEIGHT + 3, 16, TMP_SCREEN_WIDTH*2,
+						sdl_hwscreen->format->Rmask,
+						sdl_hwscreen->format->Gmask,
+						sdl_hwscreen->format->Bmask,
+						sdl_hwscreen->format->Amask);
+
+	if (sdl_tmpscreen == NULL)
+		error("sdl_tmpscreen failed");
+	
 	// keyboard cursor control, some other better place for it?
 	km.x_max = SCREEN_WIDTH * scaling - 1;
 	km.y_max = SCREEN_HEIGHT * scaling - 1;
@@ -182,11 +299,11 @@ void OSystem_SDL_Normal::unload_gfx_mode() {
 		sdl_hwscreen = NULL;
 	}
 	
-	if (_mode_flags & DF_SEPARATE_TEMPSCREEN) {
+	if (sdl_tmpscreen) {
 		free((uint16*)sdl_tmpscreen->pixels);
 		SDL_FreeSurface(sdl_tmpscreen);
+		sdl_tmpscreen = NULL;
 	}
-	sdl_tmpscreen = NULL;
 }
 
 void OSystem_SDL_Normal::update_screen() {
@@ -194,14 +311,12 @@ void OSystem_SDL_Normal::update_screen() {
 	if (sdl_hwscreen == NULL)
 		return;	// Can this really happen?
 
-	/* First make sure the mouse is drawn, if it should be drawn. */
+	// First make sure the mouse is drawn, if it should be drawn.
 	draw_mouse();
 	
-	/* Palette update in case we are NOT in "real" 8 bit color mode.
-	 * Must take place before updating the screen, since the palette must
-	 * be set up for conversion from 8bit to 16bit.
-	 */ 
-	if (((_mode_flags & DF_REAL_8BIT) == 0) && _palette_changed_last != 0) {
+	// Check whether the palette was changed in the meantime and update the
+	// screen surface accordingly. 
+	if (_palette_changed_last != 0) {
 		SDL_SetColors(sdl_screen, _cur_pal + _palette_changed_first, 
 			_palette_changed_first,
 			_palette_changed_last - _palette_changed_first);
@@ -222,7 +337,7 @@ void OSystem_SDL_Normal::update_screen() {
 		force_full = true;
 	}
 
-	/* force a full redraw if requested */
+	// Force a full redraw if requested
 	if (force_full) {
 		num_dirty_rects = 1;
 
@@ -232,20 +347,20 @@ void OSystem_SDL_Normal::update_screen() {
 		dirty_rect_list[0].h = SCREEN_HEIGHT;
 	}
 
-	/* Only draw anything if necessary */
+	// Only draw anything if necessary
 	if (num_dirty_rects > 0) {
 	
 		SDL_Rect *r; 
 		uint32 srcPitch, dstPitch;
 		SDL_Rect *last_rect = dirty_rect_list + num_dirty_rects;
 	
-		/* Convert appropriate parts of the image into 16bpp */
-		if ((_mode_flags & DF_REAL_8BIT) == 0) {
+		// Convert appropriate parts of the 8bpp image into 16bpp
+		if (!_overlay_visible) {
 			SDL_Rect dst;
 			for(r=dirty_rect_list; r!=last_rect; ++r) {
 				dst = *r;
-				dst.x++;
-				dst.y++;
+				dst.x++;	// Shift rect by one since 2xSai needs to acces the data around
+				dst.y++;	// any pixel to scale it, and we want to avoid mem access crashes.
 				if (SDL_BlitSurface(sdl_screen, r, sdl_tmpscreen, &dst) != 0)
 					error("SDL_BlitSurface failed: %s", SDL_GetError());
 			}
@@ -257,46 +372,24 @@ void OSystem_SDL_Normal::update_screen() {
 		srcPitch = sdl_tmpscreen->pitch;
 		dstPitch = sdl_hwscreen->pitch;
 	
-		if ((_mode_flags & DF_REAL_8BIT) == 0) {
-			for(r=dirty_rect_list; r!=last_rect; ++r) {
-				register int dst_y = r->y + _current_shake_pos;
-				register int dst_h = 0;
-				if (dst_y < SCREEN_HEIGHT) {
-					dst_h = r->h;
-					if (dst_h > SCREEN_HEIGHT - dst_y)
-						dst_h = SCREEN_HEIGHT - dst_y;
-					
-					r->x <<= 1;
-					dst_y <<= 1;
-					
-					_sai_func((byte*)sdl_tmpscreen->pixels + (r->x+2) + (r->y+1)*srcPitch, srcPitch, NULL, 
-						(byte*)sdl_hwscreen->pixels + r->x*scaling + dst_y*dstPitch, dstPitch, r->w, dst_h);
-				}
+		for(r=dirty_rect_list; r!=last_rect; ++r) {
+			register int dst_y = r->y + _current_shake_pos;
+			register int dst_h = 0;
+			if (dst_y < SCREEN_HEIGHT) {
+				dst_h = r->h;
+				if (dst_h > SCREEN_HEIGHT - dst_y)
+					dst_h = SCREEN_HEIGHT - dst_y;
 				
-				r->y = dst_y;
-				r->w <<= 1;
-				r->h = dst_h << 1;
-			}
-		} else {
-			for(r=dirty_rect_list; r!=last_rect; ++r) {
-				register int dst_y = r->y + _current_shake_pos;
-				register int dst_h = 0;
-				if (dst_y < SCREEN_HEIGHT) {
-					dst_h = r->h;
-					if (dst_h > SCREEN_HEIGHT - dst_y)
-						dst_h = SCREEN_HEIGHT - dst_y;
-					
-					dst_y *= scaling;
-					
-					_sai_func((byte*)sdl_tmpscreen->pixels + r->x + r->y*srcPitch, srcPitch, NULL, 
-						(byte*)sdl_hwscreen->pixels + r->x*scaling + dst_y*dstPitch, dstPitch, r->w, dst_h);
-				}
+				dst_y *= scaling;
 				
-				r->x *= scaling;
-				r->y = dst_y;
-				r->w *= scaling;
-				r->h = dst_h * scaling;
+				_scaler_proc((byte*)sdl_tmpscreen->pixels + (r->x*2+2) + (r->y+1)*srcPitch, srcPitch, NULL, 
+					(byte*)sdl_hwscreen->pixels + r->x*2*scaling + dst_y*dstPitch, dstPitch, r->w, dst_h);
 			}
+			
+			r->x *= scaling;
+			r->y = dst_y;
+			r->w *= scaling;
+			r->h = dst_h * scaling;
 		}
 	
 		if (force_full) {
@@ -308,19 +401,6 @@ void OSystem_SDL_Normal::update_screen() {
 		SDL_UnlockSurface(sdl_hwscreen);
 	}
 	
-	/* Palette update in case we are in "real" 8 bit color mode.
-	 * Must take place after the screen data was updated, since with
-	 * "real" 8bit mode, palatte changes may be visible immediatly,
-	 * and we want to avoid any ugly effects.
-	 */
-	if (_mode_flags & DF_REAL_8BIT && _palette_changed_last != 0) {
-		SDL_SetColors(sdl_hwscreen, _cur_pal + _palette_changed_first, 
-			_palette_changed_first,
-			_palette_changed_last - _palette_changed_first);
-		
-		_palette_changed_last = 0;
-	}
-	
 	if (num_dirty_rects > 0) {
 		/* Finally, blit all our changes to the screen */
 		SDL_UpdateRects(sdl_hwscreen, num_dirty_rects, dirty_rect_list);
@@ -345,13 +425,10 @@ void OSystem_SDL_Normal::hotswap_gfx_mode() {
 
 	force_full = true;
 
-	/* reset palette */
-	if (_mode_flags & DF_REAL_8BIT)
-		SDL_SetColors(sdl_hwscreen, _cur_pal, 0, 256);
-	else
-		SDL_SetColors(sdl_screen, _cur_pal, 0, 256);
+	// reset palette
+	SDL_SetColors(sdl_screen, _cur_pal, 0, 256);
 
-	/* blit image */
+	// blit image
 	OSystem_SDL_Normal::copy_rect(bak_mem, SCREEN_WIDTH, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
 	free(bak_mem);
 
@@ -372,3 +449,102 @@ uint32 OSystem_SDL_Normal::property(int param, Property *value) {
 	
 	return OSystem_SDL_Common::property(param, value);
 }
+
+
+void OSystem_SDL_Normal::show_overlay()
+{
+	// hide the mouse
+	undraw_mouse();
+
+	_overlay_visible = true;
+	clear_overlay();
+}
+
+void OSystem_SDL_Normal::hide_overlay()
+{
+	_overlay_visible = false;
+	force_full = true;
+}
+
+void OSystem_SDL_Normal::clear_overlay()
+{
+	if (!_overlay_visible)
+		return;
+	
+	// hide the mouse
+	undraw_mouse();
+
+	// Clear the overlay by making the game screen "look through" everywhere.
+	SDL_Rect src, dst;
+	src.x = src.y = 0;
+	dst.x = dst.y = 1;
+	src.w = dst.w = SCREEN_WIDTH;
+	src.h = dst.h = SCREEN_HEIGHT;
+	if (SDL_BlitSurface(sdl_screen, &src, sdl_tmpscreen, &dst) != 0)
+		error("SDL_BlitSurface failed: %s", SDL_GetError());
+
+	force_full = true;
+}
+
+void OSystem_SDL_Normal::grab_overlay(int16 *buf, int pitch)
+{
+	if (!_overlay_visible)
+		return;
+
+	if (sdl_tmpscreen == NULL)
+		return;
+
+	// hide the mouse
+	undraw_mouse();
+
+	if (SDL_LockSurface(sdl_tmpscreen) == -1)
+		error("SDL_LockSurface failed: %s.\n", SDL_GetError());
+
+	int16 *src = (int16 *)sdl_tmpscreen->pixels + TMP_SCREEN_WIDTH + 1;
+	int h = SCREEN_HEIGHT;
+	do {
+		memcpy(buf, src, SCREEN_WIDTH*2);
+		src += TMP_SCREEN_WIDTH;
+		buf += pitch;
+	} while (--h);
+
+	SDL_UnlockSurface(sdl_tmpscreen);
+}
+
+void OSystem_SDL_Normal::copy_rect_overlay(const int16 *buf, int pitch, int x, int y, int w, int h)
+{
+	if (!_overlay_visible)
+		return;
+
+	if (sdl_tmpscreen == NULL)
+		return;
+
+	// Clip the coordinates
+	if (x < 0) { w+=x; buf-=x; x = 0; }
+	if (y < 0) { h+=y; buf-=y*pitch; y = 0; }
+	if (w > SCREEN_WIDTH-x) { w = SCREEN_WIDTH - x; }
+	if (h > SCREEN_HEIGHT-y) { h = SCREEN_HEIGHT - y; }
+	if (w <= 0 || h <= 0)
+		return;
+	
+	// Mark the modified region as dirty
+	cksum_valid = false;
+	add_dirty_rect(x, y, w, h);
+
+	/* FIXME: undraw mouse only if the draw rect intersects with the mouse rect */
+	undraw_mouse();
+
+	if (SDL_LockSurface(sdl_tmpscreen) == -1)
+		error("SDL_LockSurface failed: %s.\n", SDL_GetError());
+
+	int16 *dst = (int16 *)sdl_tmpscreen->pixels + (y+1) * TMP_SCREEN_WIDTH + (x+1);
+	do {
+		memcpy(dst, buf, w*2);
+		dst += TMP_SCREEN_WIDTH;
+		buf += pitch;
+	} while (--h);
+
+	SDL_UnlockSurface(sdl_tmpscreen);
+}
+
+
diff --git a/backends/sdl/sdl_gl.cpp b/backends/sdl/sdl_gl.cpp
index b62a757d84..00d0947f32 100644
--- a/backends/sdl/sdl_gl.cpp
+++ b/backends/sdl/sdl_gl.cpp
@@ -47,6 +47,13 @@ public:
 	// Set a parameter
 	uint32 property(int param, Property *value);
 
+	// Overlay
+	virtual void show_overlay();
+	virtual void hide_overlay();
+	virtual void clear_overlay();
+	virtual void grab_overlay(int16 *buf, int pitch);
+	virtual void copy_rect_overlay(const int16 *buf, int pitch, int x, int y, int w, int h);
+
 protected:
 	FB2GL fb2gl;
 
@@ -78,22 +85,14 @@ void OSystem_SDL_GL::set_palette(const byte *colors, uint start, uint num) {
 void OSystem_SDL_GL::load_gfx_mode() {
 	int gl_flags =  FB2GL_320 | FB2GL_PITCH; 
 	force_full = true;
-	scaling = 1;
+	scaling = 2;
 	_mode_flags = 0;
-
-	_sai_func = NULL;
-	sdl_tmpscreen = NULL;
-
-	/* It's easier to work with 8 bit (256 colors) */
-	_mode_flags |= DF_REAL_8BIT;
 	
 	sdl_screen = SDL_CreateRGBSurface(SDL_SWSURFACE, SCREEN_WIDTH, SCREEN_HEIGHT, 8, 0, 0, 0, 0);
 	if (sdl_screen == NULL)
 		error("sdl_screen failed failed");
 
-	_sai_func = Normal1x;
-
-	_mode_flags = DF_WANT_RECT_OPTIM | DF_REAL_8BIT;
+	_mode_flags = DF_WANT_RECT_OPTIM;
 
 	if (_full_screen) gl_flags |= (FB2GL_FS);
 	
@@ -109,8 +108,6 @@ void OSystem_SDL_GL::load_gfx_mode() {
 	}
 
 	SDL_SetGamma(1.25,1.25,1.25);
-	  
-	sdl_tmpscreen = sdl_screen;
 }
 
 void OSystem_SDL_GL::unload_gfx_mode() {
@@ -118,12 +115,6 @@ void OSystem_SDL_GL::unload_gfx_mode() {
 		SDL_FreeSurface(sdl_screen);
 		sdl_screen = NULL; 
 	}
-
-	if (_mode_flags & DF_SEPARATE_TEMPSCREEN) {
-		free((uint16*)sdl_tmpscreen->pixels);
-		SDL_FreeSurface(sdl_tmpscreen);
-	}
-	sdl_tmpscreen = NULL;
 }
 
 void OSystem_SDL_GL::update_screen() {
@@ -150,7 +141,7 @@ void OSystem_SDL_GL::update_screen() {
 		_palette_changed_last = 0;
 	}
 
-	fb2gl.update(sdl_tmpscreen->pixels,320,200,320,0,_current_shake_pos);
+	fb2gl.update(sdl_screen->pixels,320,200,320,0,_current_shake_pos);
 
 }
 
@@ -168,7 +159,7 @@ void OSystem_SDL_GL::hotswap_gfx_mode() {
 	load_gfx_mode();
 
 	fb2gl.setPalette(0,256);
-	fb2gl.update(sdl_tmpscreen->pixels,320,200,320,0,_current_shake_pos);
+	fb2gl.update(sdl_screen->pixels,320,200,320,0,_current_shake_pos);
 
 	/* blit image */
 	copy_rect(bak_mem, SCREEN_WIDTH, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
diff --git a/common/scaler.cpp b/common/scaler.cpp
index 9a98d1e8ef..c0a2e30ef4 100644
--- a/common/scaler.cpp
+++ b/common/scaler.cpp
@@ -747,16 +747,15 @@ void AdvMame2x(uint8 *srcPtr, uint32 srcPitch, uint8 *null, uint8 *dstPtr, uint3
 }
 
 
-/* Beware! Contrary to the other functions in this file, this blits from 8 to 8 bit! */
 void Normal1x(uint8 *srcPtr, uint32 srcPitch, uint8 *null, uint8 *dstPtr, uint32 dstPitch,
 							int width, int height)
 {
-	uint8 *r;
+	uint16 *r;
 
 	while (height--) {
-		r = dstPtr;
+		r = (uint16 *)dstPtr;
 		for (int i = 0; i < width; ++i, ++r) {
-			uint8 color = *(srcPtr + i);
+			uint16 color = *(((uint16 *)srcPtr) + i);
 
 			*r = color;
 		}
@@ -765,7 +764,6 @@ void Normal1x(uint8 *srcPtr, uint32 srcPitch, uint8 *null, uint8 *dstPtr, uint32
 	}
 }
 
-/* Beware! Contrary to the other functions in this file, this blits from 8 to 8 bit! */
 void Normal2x(uint8 *srcPtr, uint32 srcPitch, uint8 *null, uint8 *dstPtr, uint32 dstPitch,
 							int width, int height)
 {
@@ -773,42 +771,42 @@ void Normal2x(uint8 *srcPtr, uint32 srcPitch, uint8 *null, uint8 *dstPtr, uint32
 
 	while (height--) {
 		r = dstPtr;
-		for (int i = 0; i < width; ++i, r += 2) {
-			uint8 color = *(srcPtr + i);
+		for (int i = 0; i < width; ++i, r += 4) {
+			uint16 color = *(((uint16 *)srcPtr) + i);
 
-			*(r) = color;
-			*(r + 1) = color;
-			*(r + dstPitch) = color;
-			*(r + dstPitch + 1) = color;
+			*(uint16 *)(r + 0) = color;
+			*(uint16 *)(r + 2) = color;
+			*(uint16 *)(r + 0 + dstPitch) = color;
+			*(uint16 *)(r + 2 + dstPitch) = color;
 		}
 		srcPtr += srcPitch;
 		dstPtr += dstPitch << 1;
 	}
 }
 
-/* Beware! Contrary to the other functions in this file, this blits from 8 to 8 bit! */
 void Normal3x(uint8 *srcPtr, uint32 srcPitch, uint8 *null, uint8 *dstPtr, uint32 dstPitch,
 							int width, int height)
 {
 	uint8 *r;
-	uint32 dstPitch2 = dstPitch << 1;
+	uint32 dstPitch2 = dstPitch * 2;
+	uint32 dstPitch3 = dstPitch * 3;
 
 	while (height--) {
 		r = dstPtr;
-		for (int i = 0; i < width; ++i, r += 3) {
-			uint8 color = *(srcPtr + i);
-
-			*(r + 0) = color;
-			*(r + 1) = color;
-			*(r + 2) = color;
-			*(r + 0 + dstPitch) = color;
-			*(r + 1 + dstPitch) = color;
-			*(r + 2 + dstPitch) = color;
-			*(r + 0 + dstPitch2) = color;
-			*(r + 1 + dstPitch2) = color;
-			*(r + 2 + dstPitch2) = color;
+		for (int i = 0; i < width; ++i, r += 6) {
+			uint16 color = *(((uint16 *)srcPtr) + i);
+
+			*(uint16 *)(r + 0) = color;
+			*(uint16 *)(r + 2) = color;
+			*(uint16 *)(r + 4) = color;
+			*(uint16 *)(r + 0 + dstPitch) = color;
+			*(uint16 *)(r + 2 + dstPitch) = color;
+			*(uint16 *)(r + 4 + dstPitch) = color;
+			*(uint16 *)(r + 0 + dstPitch2) = color;
+			*(uint16 *)(r + 2 + dstPitch2) = color;
+			*(uint16 *)(r + 4 + dstPitch2) = color;
 		}
 		srcPtr += srcPitch;
-		dstPtr += dstPitch * 3;
+		dstPtr += dstPitch3;
 	}
 }
diff --git a/common/system.h b/common/system.h
index 97e7ebcca2..f3fcea129a 100644
--- a/common/system.h
+++ b/common/system.h
@@ -158,6 +158,13 @@ public:
 
 	// Quit
 	virtual void quit() = 0;
+	
+	// Overlay
+	virtual void show_overlay() = 0;
+	virtual void hide_overlay() = 0;
+	virtual void clear_overlay() = 0;
+	virtual void grab_overlay(int16 *buf, int pitch) = 0;
+	virtual void copy_rect_overlay(const int16 *buf, int pitch, int x, int y, int w, int h) = 0;
 };
 
 
diff --git a/gui/dialog.cpp b/gui/dialog.cpp
index 54b50e8958..e1886af83d 100644
--- a/gui/dialog.cpp
+++ b/gui/dialog.cpp
@@ -45,33 +45,6 @@
  * ...
  */
 
-Dialog::~Dialog()
-{
-	teardownScreenBuf();
-}
-
-void Dialog::setupScreenBuf()
-{
-	// Create _screenBuf if it doesn't already exist
-	if (!_screenBuf)
-		_screenBuf = new byte[g_scumm->_realWidth * g_scumm->_realHeight];
-	
-	// Draw the fixed parts of the dialog: background and border.
-	_gui->blendRect(_x, _y, _w, _h, _gui->_bgcolor);
-	_gui->box(_x, _y, _w, _h);
-	
-	// Finally blit this to _screenBuf
-	_gui->blitTo(_screenBuf, _x, _y, _w, _h); 
-}
-
-void Dialog::teardownScreenBuf()
-{
-	if (_screenBuf) {
-		delete [] _screenBuf;
-		_screenBuf = 0;
-	}
-}
-
 void Dialog::open()
 {
 	Widget *w = _firstWidget;
@@ -112,18 +85,15 @@ void Dialog::draw()
 	if (!isVisible())
 		return;
 
-	if (_screenBuf) {
-		_gui->blitFrom(_screenBuf, _x, _y, _w, _h); 
-	} else {
-		_gui->fillRect(_x, _y, _w, _h, _gui->_bgcolor);
-		_gui->box(_x, _y, _w, _h);
-	}
-	_gui->addDirtyRect(_x, _y, _w, _h);
+	_gui->blendRect(_x, _y, _w, _h, _gui->_bgcolor);
+	_gui->box(_x, _y, _w, _h);
 
 	while (w) {
 		w->draw();
 		w = w->_next;
 	}
+
+	_gui->addDirtyRect(_x, _y, _w, _h);
 }
 
 void Dialog::handleMouseDown(int x, int y, int button, int clickCount)
@@ -314,8 +284,8 @@ enum {
  *   method to Dialog for that.
  */
 
-SaveLoadDialog::SaveLoadDialog(NewGui *gui)
-	: Dialog (gui, 30, 20, 260, 124)
+SaveLoadDialog::SaveLoadDialog(NewGui *gui, Scumm *scumm)
+	: Dialog (gui, 30, 20, 260, 124), _scumm(scumm)
 {
 	addResText(10, 7, 240, 16, 1);
 //  addResText(10, 7, 240, 16, 2);
@@ -333,10 +303,9 @@ SaveLoadDialog::SaveLoadDialog(NewGui *gui)
 	// Get savegame names
 	ScummVM::StringList l;
 	char name[32];
-	Scumm *s = _gui->getScumm();
 
 	for (int i = 0; i <= 80; i++) {		// 80 - got this value from the old GUI
-		s->getSavegameName(i, name);
+		_scumm->getSavegameName(i, name);
 		l.push_back(name);
 	}
 
@@ -349,7 +318,7 @@ void SaveLoadDialog::handleCommand(CommandSender *sender, uint32 cmd, uint32 dat
 	case kListItemChangedCmd:
 	case kSaveCmd:
 		if (_savegameList->getSelected() >= 1 && !_savegameList->getSelectedString().isEmpty()) {
-			Scumm *s = _gui->getScumm();
+			Scumm *s = _scumm;
 			s->_saveLoadSlot = _savegameList->getSelected();
 			s->_saveLoadCompatible = false;
 			s->_saveLoadFlag = 1;		// 1 for save, I assume (Painelf)
@@ -360,7 +329,7 @@ void SaveLoadDialog::handleCommand(CommandSender *sender, uint32 cmd, uint32 dat
 	case kListItemDoubleClickedCmd:
 	case kLoadCmd:
 		if (_savegameList->getSelected() >= 0 && !_savegameList->getSelectedString().isEmpty()) {
-			Scumm *s = _gui->getScumm();
+			Scumm *s = _scumm;
 			s->_saveLoadSlot = _savegameList->getSelected();
 			s->_saveLoadCompatible = false;
 			s->_saveLoadFlag = 2;		// 2 for load. Magic number anyone?
@@ -374,8 +343,7 @@ void SaveLoadDialog::handleCommand(CommandSender *sender, uint32 cmd, uint32 dat
 		_gui->optionsDialog();
 		break;
 	case kQuitCmd: {
-			Scumm *s = _gui->getScumm();
-			s->_system->quit();
+			_scumm->_system->quit();
 		}
 		break;
 	default:
@@ -441,8 +409,8 @@ PauseDialog::PauseDialog(NewGui *gui)
 	addResText(4, 4, 220, 16, 10);
 }
 
-SoundDialog::SoundDialog(NewGui *gui)
-	: Dialog (gui, 30, 20, 260, 110)
+SoundDialog::SoundDialog(NewGui *gui, Scumm *scumm)
+	: Dialog (gui, 30, 20, 260, 110), _scumm(scumm)
 {
 
 	// set up dialog
@@ -471,14 +439,12 @@ SoundDialog::SoundDialog(NewGui *gui)
 
 void SoundDialog::open()
 {
-	Scumm	*scumm = _gui->getScumm();
-	
 	Dialog::open();
 
 	// get current variables
-	_soundVolumeMaster = scumm->_sound->_sound_volume_master;
-	_soundVolumeMusic = scumm->_sound->_sound_volume_music;
-	_soundVolumeSfx = scumm->_sound->_sound_volume_sfx;
+	_soundVolumeMaster = _scumm->_sound->_sound_volume_master;
+	_soundVolumeMusic = _scumm->_sound->_sound_volume_music;
+	_soundVolumeSfx = _scumm->_sound->_sound_volume_sfx;
 
 	masterVolumeSlider->setValue(_soundVolumeMaster);
 	musicVolumeSlider->setValue(_soundVolumeMusic);
@@ -509,17 +475,15 @@ void SoundDialog::handleCommand(CommandSender *sender, uint32 cmd, uint32 data)
 		sfxVolumeLabel->draw();
 		break;
 	case kOKCmd: {
-		Scumm	*scumm = _gui->getScumm();
-		
 		// FIXME: Look at Fingolfins comments in Gui::handleSoundDialogCommand(), gui.cpp 
-		scumm->_sound->_sound_volume_master = _soundVolumeMaster;	// Master
-		scumm->_sound->_sound_volume_music = _soundVolumeMusic;	// Music
-		scumm->_sound->_sound_volume_sfx = _soundVolumeSfx;	// SFX
+		_scumm->_sound->_sound_volume_master = _soundVolumeMaster;	// Master
+		_scumm->_sound->_sound_volume_music = _soundVolumeMusic;	// Music
+		_scumm->_sound->_sound_volume_sfx = _soundVolumeSfx;	// SFX
 		
-		scumm->_imuse->set_music_volume(_soundVolumeMusic);
-		scumm->_imuse->set_master_volume(_soundVolumeMaster);
-		scumm->_mixer->setVolume(_soundVolumeSfx);
-		scumm->_mixer->setMusicVolume(_soundVolumeMusic);
+		_scumm->_imuse->set_music_volume(_soundVolumeMusic);
+		_scumm->_imuse->set_master_volume(_soundVolumeMaster);
+		_scumm->_mixer->setVolume(_soundVolumeSfx);
+		_scumm->_mixer->setMusicVolume(_soundVolumeMusic);
 		
 		scummcfg->setInt("master_volume", _soundVolumeMaster);
 		scummcfg->setInt("music_volume", _soundVolumeMusic);
diff --git a/gui/dialog.h b/gui/dialog.h
index 4d5dd82d0b..3d1577b9e3 100644
--- a/gui/dialog.h
+++ b/gui/dialog.h
@@ -26,6 +26,7 @@
 #include "ListWidget.h"
 
 class NewGui;
+class Scumm;
 
 #define RES_STRING(id)		_gui->queryResString(id)
 #define CUSTOM_STRING(id)	_gui->queryCustomString(id)
@@ -45,15 +46,14 @@ protected:
 	Widget	*_firstWidget;
 	Widget	*_mouseWidget;
 	Widget  *_focusedWidget;
-	byte	*_screenBuf;
 	bool	_visible;
 
 public:
 	Dialog(NewGui *gui, int x, int y, int w, int h)
 		: _gui(gui), _x(x), _y(y), _w(w), _h(h), _firstWidget(0),
-		  _mouseWidget(0), _focusedWidget(0), _screenBuf(0), _visible(false)
+		  _mouseWidget(0), _focusedWidget(0), _visible(false)
 		{}
-	virtual ~Dialog();
+	virtual ~Dialog() {};
 
 	virtual void open();
 	virtual void close();
@@ -70,9 +70,6 @@ public:
 	
 	NewGui	*getGui()	{ return _gui; }
 	
-	virtual void	setupScreenBuf();
-	virtual void	teardownScreenBuf();
-
 	bool isVisible() const		{ return _visible; }
 
 protected:
@@ -85,24 +82,25 @@ protected:
 
 class SaveLoadDialog : public Dialog {
 public:
-	SaveLoadDialog(NewGui *gui);
+	SaveLoadDialog(NewGui *gui, Scumm *scumm);
 
 	virtual void handleCommand(CommandSender *sender, uint32 cmd, uint32 data);
 
 protected:
+	Scumm *_scumm;
 	ListWidget	*_savegameList;
 };
 
 
-class SoundDialog;
-class KeysDialog;
-class MiscDialog;
-
 class AboutDialog : public Dialog {
 public:
 	AboutDialog(NewGui *gui);
 };
 
+class SoundDialog;
+class KeysDialog;
+class MiscDialog;
+
 class OptionsDialog : public Dialog {
 protected:
 	SoundDialog		*_soundDialog;
@@ -138,7 +136,7 @@ public:
 
 class SoundDialog : public Dialog {
 public:
-	SoundDialog(NewGui *gui);
+	SoundDialog(NewGui *gui, Scumm *scumm);
 
 	enum {
 		kMasterVolumeChanged	= 'mavc',
@@ -153,6 +151,8 @@ public:
 	virtual void handleCommand(CommandSender *sender, uint32 cmd, uint32 data);
 
 protected:
+	Scumm *_scumm;
+	
 	int _soundVolumeMaster;
 	int _soundVolumeMusic;
 	int _soundVolumeSfx;
diff --git a/gui/newgui.cpp b/gui/newgui.cpp
index 9da918525e..89a9cd49bb 100644
--- a/gui/newgui.cpp
+++ b/gui/newgui.cpp
@@ -37,11 +37,24 @@
  * - ...
  */
 
-NewGui::NewGui(Scumm *s) : _s(s), _use_alpha_blending(false),
-	_need_redraw(false),_prepare_for_gui(true),
+// FIXME - this macro assumes that we use 565 mode. But what if we are in 555 mode?
+#define RGB_TO_16(r,g,b)	(((((r)>>3)&0x1F) << 11) | ((((g)>>2)&0x3F) << 5) | (((b)>>3)&0x1F))
+//#define RGB_TO_16(r,g,b)	(((((r)>>3)&0x1F) << 10) | ((((g)>>3)&0x1F) << 5) | (((b)>>3)&0x1F))
+
+#define RED_FROM_16(x)		((((x)>>11)&0x1F) << 3)
+#define GREEN_FROM_16(x)	((((x)>>5)&0x3F) << 2)
+#define BLUE_FROM_16(x)		(((x)&0x1F) << 3)
+
+//#define RED_FROM_16(x)	((((x)>>10)&0x1F) << 3)
+//#define GREEN_FROM_16(x)	((((x)>>5)&0x1F) << 3)
+//#define BLUE_FROM_16(x)	(((x)&0x1F) << 3)
+
+
+NewGui::NewGui(Scumm *s) : _s(s), _system(s->_system), _screen(0),
+	_use_alpha_blending(true), _need_redraw(false),_prepare_for_gui(true),
 	_pauseDialog(0), _saveLoadDialog(0), _aboutDialog(0), _optionsDialog(0),
 	_currentKeyDown(0)
-{	
+{
 }
 
 void NewGui::pauseDialog()
@@ -54,7 +67,7 @@ void NewGui::pauseDialog()
 void NewGui::saveloadDialog()
 {
 	if (!_saveLoadDialog)
-		_saveLoadDialog = new SaveLoadDialog(this);
+		_saveLoadDialog = new SaveLoadDialog(this, _s);
 	_saveLoadDialog->open();
 }
 
@@ -75,7 +88,7 @@ void NewGui::optionsDialog()
 void NewGui::soundDialog()
 {
 	if (!_soundDialog)
-		_soundDialog = new SoundDialog(this);
+		_soundDialog = new SoundDialog(this, _s);
 	_soundDialog->open();
 }
 
@@ -85,22 +98,14 @@ void NewGui::loop()
 	int i;
 	
 	if (_prepare_for_gui) {
-		ClearBlendCache(_s->_currentPalette, 128);
 		saveState();
-		if (_use_alpha_blending)
-			activeDialog->setupScreenBuf();
-#if 1
-		// FIXME - hack to encode our own custom GUI colors. Since we have to live
-		// with a given 8 bit palette, the result is not always as nice as one
-		// would wish, but this is just an experiment after all.
-		_bgcolor = RGBMatch(_s->_currentPalette, 0, 0, 0);
-	
-		_color = RGBMatch(_s->_currentPalette, 80, 80, 80);
-		_shadowcolor = RGBMatch(_s->_currentPalette, 64, 64, 64);
-	
-		_textcolor = RGBMatch(_s->_currentPalette, 32, 192, 32);
-		_textcolorhi = RGBMatch(_s->_currentPalette, 0, 256, 0);
-#endif
+
+		// Setup some default GUI colors
+		_bgcolor = RGB_TO_16(0, 0, 0);
+		_color = RGB_TO_16(80, 80, 80);
+		_shadowcolor = RGB_TO_16(64, 64, 64);
+		_textcolor = RGB_TO_16(32, 192, 32);
+		_textcolorhi = RGB_TO_16(0, 255, 0);
 
 		_eventList.clear();
 		_currentKeyDown = 0;
@@ -115,6 +120,10 @@ void NewGui::loop()
 	activeDialog->handleTickle();
 
 	if (_need_redraw) {
+		// Restore the overlay to its initial state, then draw all dialogs.
+		// This is necessary to get the blending right.
+		_system->clear_overlay();
+		_system->grab_overlay(_screen, _screen_pitch);
 		for (i = 0; i < _dialogStack.size(); i++)
 			_dialogStack[i]->draw();
 		_need_redraw = false;
@@ -152,7 +161,7 @@ void NewGui::loop()
 				// We don't distinguish between mousebuttons (for now at least)
 				case OSystem::EVENT_LBUTTONDOWN:
 				case OSystem::EVENT_RBUTTONDOWN: {
-					uint32 time = _s->_system->get_msecs();
+					uint32 time = _system->get_msecs();
 					if (_lastClick.count && (time < _lastClick.time + kDoubleClickDelay)
 					      && ABS(_lastClick.x - t.mouse.x) < 3
 					      && ABS(_lastClick.y - t.mouse.y) < 3) {
@@ -208,10 +217,16 @@ void NewGui::saveState()
 	_old_cursorHeight = _s->_cursorHeight;
 	_old_cursorHotspotX = _s->_cursorHotspotX;
 	_old_cursorHotspotY = _s->_cursorHotspotY;
-	_old_cursor_mode = _s->_system->show_mouse(true);
+	_old_cursor_mode = _system->show_mouse(true);
 
 	_s->_cursorAnimate++;
 	_s->gdi._cursorActive = 1;
+	
+	// TODO - add getHeight & getWidth methods to OSystem
+	_system->show_overlay();
+	_screen = new int16[_s->_realWidth * _s->_realHeight];
+	_screen_pitch = _s->_realWidth;
+	_system->grab_overlay(_screen, _screen_pitch);
 }
 
 void NewGui::restoreState()
@@ -228,17 +243,21 @@ void NewGui::restoreState()
 	_s->_cursorHotspotY = _old_cursorHotspotY;
 	_s->updateCursor();
 
-	_s->_system->show_mouse(_old_cursor_mode);
+	_system->show_mouse(_old_cursor_mode);
 
 	_s->_sound->pauseSounds(_old_soundsPaused);
+
+	_system->hide_overlay();
+	if (_screen) {
+		delete _screen;
+		_screen = 0;
+	}
 }
 
 void NewGui::openDialog(Dialog *dialog)
 {
 	if (_dialogStack.empty())
 		_prepare_for_gui = true;
-	else if (_use_alpha_blending)
-		dialog->setupScreenBuf();
 
 	_dialogStack.push(dialog);
 	_need_redraw = true;
@@ -250,10 +269,6 @@ void NewGui::closeTopDialog()
 	if (_dialogStack.empty())
 		return;
 	
-	// Tear down its screenBuf
-	if (_use_alpha_blending)
-		_dialogStack.top()->teardownScreenBuf();
-	
 	// Remove the dialog from the stack
 	_dialogStack.pop();
 	if (_dialogStack.empty())
@@ -304,15 +319,9 @@ const char *NewGui::queryCustomString(int stringno)
 #pragma mark -
 
 
-byte *NewGui::getBasePtr(int x, int y)
+int16 *NewGui::getBasePtr(int x, int y)
 {
-	VirtScreen *vs = _s->findVirtScreen(y);
-
-	if (vs == NULL)
-		return NULL;
-
-	return vs->screenPtr + x + (y - vs->topline) * _s->_realWidth +
-		_s->_screenStartStrip * 8 + (_s->camera._cur.y - (_s->_realHeight / 2)) * _s->_realWidth;
+	return _screen + x + y * _screen_pitch;
 }
 
 void NewGui::box(int x, int y, int width, int height)
@@ -328,9 +337,9 @@ void NewGui::box(int x, int y, int width, int height)
 	vline(x + width - 2, y + 1, y + height - 1, _shadowcolor);
 }
 
-void NewGui::line(int x, int y, int x2, int y2, byte color)
+void NewGui::line(int x, int y, int x2, int y2, int16 color)
 {
-	byte *ptr;
+	int16 *ptr;
 
 	if (x2 < x)
 		x2 ^= x ^= x2 ^= x;					// Swap x2 and x
@@ -347,7 +356,7 @@ void NewGui::line(int x, int y, int x2, int y2, byte color)
 		/* vertical line */
 		while (y++ <= y2) {
 			*ptr = color;
-			ptr += _s->_realWidth;
+			ptr += _screen_pitch;
 		}
 	} else if (y == y2) {
 		/* horizontal line */
@@ -357,53 +366,61 @@ void NewGui::line(int x, int y, int x2, int y2, byte color)
 	}
 }
 
-void NewGui::blendRect(int x, int y, int w, int h, byte color)
+void NewGui::blendRect(int x, int y, int w, int h, int16 color)
 {
-	byte *ptr = getBasePtr(x, y);
+	int r = RED_FROM_16(color);
+	int g = GREEN_FROM_16(color);
+	int b = BLUE_FROM_16(color);
+	int16 *ptr = getBasePtr(x, y);
 	if (ptr == NULL)
 		return;
 
 	while (h--) {
 		for (int i = 0; i < w; i++) {
-			ptr[i] = Blend(ptr[i], color, _s->_currentPalette);
+			ptr[i] = RGB_TO_16((RED_FROM_16(ptr[i])+r)/2,
+			                   (GREEN_FROM_16(ptr[i])+g)/2,
+			                   (BLUE_FROM_16(ptr[i])+b)/2);
+//			ptr[i] = color;
 		}
-		ptr += _s->_realWidth;
+		ptr += _screen_pitch;
 	}
 }
 
-void NewGui::fillRect(int x, int y, int w, int h, byte color)
+void NewGui::fillRect(int x, int y, int w, int h, int16 color)
 {
-	byte *ptr = getBasePtr(x, y);
+	int i;
+	int16 *ptr = getBasePtr(x, y);
 	if (ptr == NULL)
 		return;
 
 	while (h--) {
-		for (int i = 0; i < w; i++) {
+		for (i = 0; i < w; i++) {
 			ptr[i] = color;
 		}
-		ptr += _s->_realWidth;
+		ptr += _screen_pitch;
 	}
 }
 
-void NewGui::checkerRect(int x, int y, int w, int h, byte color)
+void NewGui::checkerRect(int x, int y, int w, int h, int16 color)
 {
-	byte *ptr = getBasePtr(x, y);
+	int i;
+	int16 *ptr = getBasePtr(x, y);
 	if (ptr == NULL)
 		return;
 
 	while (h--) {
-		for (int i = 0; i < w; i++) {
+		for (i = 0; i < w; i++) {
 			if ((h ^ i) & 1)
 				ptr[i] = color;
 		}
-		ptr += _s->_realWidth;
+		ptr += _screen_pitch;
 	}
 }
 
-void NewGui::frameRect(int x, int y, int w, int h, byte color)
+void NewGui::frameRect(int x, int y, int w, int h, int16 color)
 {
 	int i;
-	byte *ptr, *basePtr = getBasePtr(x, y);
+	int16 *ptr, *basePtr = getBasePtr(x, y);
 	if (basePtr == NULL)
 		return;
 
@@ -411,57 +428,57 @@ void NewGui::frameRect(int x, int y, int w, int h, byte color)
 	for (i = 0; i < w; i++, ptr++)
 		*ptr = color;
 	ptr--;
-	for (i = 0; i < h; i++, ptr += _s->_realWidth)
+	for (i = 0; i < h; i++, ptr += _screen_pitch)
 		*ptr = color;
 	ptr = basePtr;
-	for (i = 0; i < h; i++, ptr += _s->_realWidth)
+	for (i = 0; i < h; i++, ptr += _screen_pitch)
 		*ptr = color;
-	ptr -= _s->_realWidth;
+	ptr -= _screen_pitch;
 	for (i = 0; i < w; i++, ptr++)
 		*ptr = color;
 }
 
 void NewGui::addDirtyRect(int x, int y, int w, int h)
 {
-	VirtScreen *vs = _s->findVirtScreen(y);
-
-	if (vs != NULL)
-		_s->setVirtscreenDirty(vs, x, y, x + w, y + h);
+	// For now we don't keep yet another list of dirty rects but simply
+	// blit the affected area directly to the overlay. At least for our current
+	// GUI/widget/dialog code that is just fine.
+	int16 *buf = getBasePtr(x, y);
+	_system->copy_rect_overlay(buf, _screen_pitch, x, y, w, h);
 }
 
-void NewGui::drawChar(const char str, int xx, int yy)
+void NewGui::drawChar(const char str, int xx, int yy, int16 color)
 {
 	unsigned int buffer = 0, mask = 0, x, y;
 	byte *tmp;
-	int tempc = _color;
-	_color = _textcolor;
 
 	tmp = &guifont[0];
 	tmp += 224 + (str + 1) * 8;
 
-	byte *ptr = getBasePtr(xx, yy);
+	int16 *ptr = getBasePtr(xx, yy);
 	if (ptr == NULL)
 		return;
 
 	for (y = 0; y < 8; y++) {
 		for (x = 0; x < 8; x++) {
-			unsigned char color;
+			unsigned char c;
 			if ((mask >>= 1) == 0) {
 				buffer = *tmp++;
 				mask = 0x80;
 			}
-			color = ((buffer & mask) != 0);
-			if (color)
-				ptr[x] = _color;
+			c = ((buffer & mask) != 0);
+			if (c)
+				ptr[x] = color;
 		}
-		ptr += _s->_realWidth;
+		ptr += _screen_pitch;
 	}
-	_color = tempc;
-
 }
 
-void NewGui::drawString(const char *str, int x, int y, int w, byte color, int align)
+void NewGui::drawString(const char *str, int x, int y, int w, int16 color, int align)
 {
+#if 1
+	if (0) {
+#else
 	if (_s->_gameId) {						/* If a game is active.. */
 		StringTab *st = &_s->string[5];
 		st->charset = 1;
@@ -480,22 +497,23 @@ void NewGui::drawString(const char *str, int x, int y, int w, byte color, int al
 	
 		_s->_messagePtr = (byte *)str;
 		_s->drawString(5);
+#endif
 	} else {
 		// FIXME - support center/right align, use nicer custom font.
 		// Ultimately, we might want to *always* draw our messages this way,
 		// but only if we have a nice font.
 		uint len = strlen(str);
 		for (uint letter = 0; letter < len; letter++)
-			drawChar(str[letter], x + (letter * 8), y);
+			drawChar(str[letter], x + (letter * 8), y, color);
 	}
 }
 
 /*
  * Draw an 8x8 bitmap at location (x,y)
  */
-void NewGui::drawBitmap(uint32 bitmap[8], int x, int y, byte color)
+void NewGui::drawBitmap(uint32 bitmap[8], int x, int y, int16 color)
 {
-	byte *ptr = getBasePtr(x, y);
+	int16 *ptr = getBasePtr(x, y);
 	if (ptr == NULL)
 		return;
 
@@ -506,39 +524,6 @@ void NewGui::drawBitmap(uint32 bitmap[8], int x, int y, byte color)
 				ptr[x2] = color;
 			mask >>= 4;
 		}
-		ptr += _s->_realWidth;
-	}
-}
-
-void NewGui::blitTo(byte buffer[320*200], int x, int y, int w, int h)
-{
-	byte *dstPtr = buffer + x + y * _s->_realWidth;
-	byte *srcPtr = getBasePtr(x, y);
-	if (srcPtr == NULL)
-		return;
-
-	while (h--) {
-		for (int i = 0; i < w; i++) {
-			*dstPtr++ = *srcPtr++;
-		}
-		dstPtr += _s->_realWidth - w;
-		srcPtr += _s->_realWidth - w;
+		ptr += _screen_pitch;
 	}
 }
-
-void NewGui::blitFrom(byte buffer[320*200], int x, int y, int w, int h)
-{
-	byte *srcPtr = buffer + x + y * _s->_realWidth;
-	byte *dstPtr = getBasePtr(x, y);
-	if (dstPtr == NULL)
-		return;
-
-	while (h--) {
-		for (int i = 0; i < w; i++) {
-			*dstPtr++ = *srcPtr++;
-		}
-		dstPtr += _s->_realWidth - w;
-		srcPtr += _s->_realWidth - w;
-	}
-}
-
diff --git a/gui/newgui.h b/gui/newgui.h
index 0b0aef913a..0df581d31b 100644
--- a/gui/newgui.h
+++ b/gui/newgui.h
@@ -63,10 +63,10 @@ typedef ScummVM::List<OSystem::Event> EventList;
 class NewGui {
 	friend class Dialog;
 public:
-	byte _color, _shadowcolor;
-	byte _bgcolor;
-	byte _textcolor;
-	byte _textcolorhi;
+	int16 _color, _shadowcolor;
+	int16 _bgcolor;
+	int16 _textcolor;
+	int16 _textcolorhi;
 
 	// Dialogs
 	void pauseDialog();
@@ -82,11 +82,13 @@ public:
 	NewGui(Scumm *s);
 
 	void handleEvent(const OSystem::Event &event) { _eventList.push_back(event); }
-	
-	Scumm *getScumm() { return _s; }
 
 protected:
 	Scumm		*_s;
+	OSystem		*_system;
+	int16		*_screen;
+	int			_screen_pitch;
+	
 	bool		_use_alpha_blending;
 	bool		_need_redraw;
 	bool		_prepare_for_gui;
@@ -129,20 +131,18 @@ protected:
 
 public:
 	// Drawing
-	byte *getBasePtr(int x, int y);
+	int16 *getBasePtr(int x, int y);
 	void box(int x, int y, int width, int height);
-	void line(int x, int y, int x2, int y2, byte color);
-	void blendRect(int x, int y, int w, int h, byte color);
-	void fillRect(int x, int y, int w, int h, byte color);
-	void checkerRect(int x, int y, int w, int h, byte color);
-	void frameRect(int x, int y, int w, int h, byte color);
+	void line(int x, int y, int x2, int y2, int16 color);
+	void blendRect(int x, int y, int w, int h, int16 color);
+	void fillRect(int x, int y, int w, int h, int16 color);
+	void checkerRect(int x, int y, int w, int h, int16 color);
+	void frameRect(int x, int y, int w, int h, int16 color);
 	void addDirtyRect(int x, int y, int w, int h);
-	void drawChar(const char c, int x, int y);
-	void drawString(const char *str, int x, int y, int w, byte color, int align = kTextAlignLeft);
+	void drawChar(const char c, int x, int y, int16 color);
+	void drawString(const char *str, int x, int y, int w, int16 color, int align = kTextAlignLeft);
 
-	void drawBitmap(uint32 bitmap[8], int x, int y, byte color);
-	void blitTo(byte buffer[320*200], int x, int y, int w, int h);
-	void blitFrom(byte buffer[320*200], int x, int y, int w, int h);
+	void drawBitmap(uint32 bitmap[8], int x, int y, int16 color);
 
 	// Query a string from the resources
 	const char *queryResString(int stringno);
diff --git a/gui/widget.cpp b/gui/widget.cpp
index e822617460..f6aedbad76 100644
--- a/gui/widget.cpp
+++ b/gui/widget.cpp
@@ -58,9 +58,6 @@ void Widget::draw()
 	
 	// Now perform the actual widget draw
 	drawWidget(_flags & WIDGET_HILITED);
-	
-	// Flag the draw area as dirty
-	gui->addDirtyRect(_x, _y, _w, _h);
 
 	// Restore x/y
 	if (_flags & WIDGET_BORDER) {
@@ -68,6 +65,10 @@ void Widget::draw()
 		_y -= 4;
 		_w += 8;
 	}
+	
+	// Flag the draw area as dirty
+	gui->addDirtyRect(_x, _y, _w, _h);
+
 	_x -= _boss->_x;
 	_y -= _boss->_y;
 }