2 files changed, 42 insertions, 3 deletions
diff --git a/engines/glk/frotz/processor.h b/engines/glk/frotz/processor.h
index dcf39869c1..5d6d4487f9 100644
--- a/engines/glk/frotz/processor.h
+++ b/engines/glk/frotz/processor.h
@@ -549,7 +549,6 @@ protected:
 
 	/**
 	 * Map a Unicode character onto the ZSCII alphabet.
-	 *
 	 */
 	zbyte translate_to_zscii(zchar c);
 
@@ -668,6 +667,26 @@ protected:
 	zchar unicode_tolower(zchar c);
 
 	/**@}*/
+
+	/**
+	 * \defgroup Window/V6 Opcode methods
+	 * @{
+	 */
+
+	/**
+	 * Return the window number in zargs[0]. In V6 only, -3 refers to the
+	 * current window.
+	 */
+	zword winarg0();
+
+	/**
+	 * Return the (optional) window number in zargs[2]. -3 refers to the
+	 * current window. This optional window number was only used by some
+	 * V6 opcodes: set_cursor, set_margins, set_colour.
+	 */
+	zword winarg2();
+
+	 /**@}*/
 protected:
 	/**
 	 * \defgroup General Opcode methods
diff --git a/engines/glk/frotz/processor_windows.cpp b/engines/glk/frotz/processor_windows.cpp
index 34c3be1fdb..5e24ac818a 100644
--- a/engines/glk/frotz/processor_windows.cpp
+++ b/engines/glk/frotz/processor_windows.cpp
@@ -255,7 +255,7 @@ void Processor::z_get_wind_prop() {
 
 	}
 	else
-		runtime_error(ERR_ILL_WIN_PROP);
+		runtimeError(ERR_ILL_WIN_PROP);
 #endif
 }
 
@@ -264,7 +264,7 @@ void Processor::z_put_wind_prop() {
 	flush_buffer();
 
 	if (zargs[1] >= 16)
-		runtime_error(ERR_ILL_WIN_PROP);
+		runtimeError(ERR_ILL_WIN_PROP);
 
 	((zword *)(wp + winarg0()))[zargs[1]] = zargs[2];
 #endif
@@ -309,5 +309,25 @@ void Processor::z_picture_table() {
 	 */
 }
 
+zword Processor::winarg0() {
+	if (h_version == V6 && (short)zargs[0] == -3)
+		return cwin;
+
+	if (zargs[0] >= ((h_version == V6) ? 8 : 2))
+		runtimeError(ERR_ILL_WIN);
+
+	return zargs[0];
+}
+
+zword Processor::winarg2() {
+	if (zargc < 3 || (short)zargs[2] == -3)
+		return cwin;
+
+	if (zargs[2] >= 8)
+		runtimeError(ERR_ILL_WIN);
+
+	return zargs[2];
+}
+
 } // End of namespace Scott
 } // End of namespace Glk