2 files changed, 52 insertions, 16 deletions

diff --git a/engines/sci/graphics/screen_item32.cpp b/engines/sci/graphics/screen_item32.cpp
index d2673d40b3..c1644a5ea3 100644
--- a/engines/sci/graphics/screen_item32.cpp
+++ b/engines/sci/graphics/screen_item32.cpp
@@ -657,23 +657,43 @@ ScreenItem *ScreenItemList::findByObject(const reg_t object) const {
 	return *screenItemIt;
 }
 void ScreenItemList::sort() {
-	// TODO: SCI engine used _unsorted as an array of indexes into the
-	// list itself and then performed the same swap operations on the
-	// _unsorted array as the _storage array during sorting, but the
-	// only reason to do this would be if some of the pointers in the
-	// list were replaced so the pointer values themselves couldn’t
-	// simply be recorded and then restored later. It is not yet
-	// verified whether this simplification of the sort/unsort is
-	// safe.
+	if (size() < 2) {
+		return;
+	}
+
 	for (size_type i = 0; i < size(); ++i) {
-		_unsorted[i] = (*this)[i];
+		_unsorted[i] = i;
 	}
 
-	Common::sort(begin(), end(), sortHelper);
+	for (size_type i = size() - 1; i > 0; --i) {
+		bool swap = false;
+
+		for (size_type j = 0; j < i; ++j)  {
+			value_type &a = operator[](j);
+			value_type &b = operator[](j + 1);
+
+			if (a == nullptr || *a > *b) {
+				SWAP(a, b);
+				SWAP(_unsorted[j], _unsorted[j + 1]);
+				swap = true;
+			}
+		}
+
+		if (!swap) {
+			break;
+		}
+	}
 }
 void ScreenItemList::unsort() {
+	if (size() < 2) {
+		return;
+	}
+
 	for (size_type i = 0; i < size(); ++i) {
-		(*this)[i] = _unsorted[i];
+		while (_unsorted[i] != i) {
+			SWAP(operator[](_unsorted[i]), operator[](i));
+			SWAP(_unsorted[_unsorted[i]], _unsorted[i]);
+		}
 	}
 }
 
diff --git a/engines/sci/graphics/screen_item32.h b/engines/sci/graphics/screen_item32.h
index eef2f488a5..2e44e418ce 100644
--- a/engines/sci/graphics/screen_item32.h
+++ b/engines/sci/graphics/screen_item32.h
@@ -236,6 +236,24 @@ public:
 		return false;
 	}
 
+	inline bool operator>(const ScreenItem &other) const {
+		if (_priority > other._priority) {
+			return true;
+		}
+
+		if (_priority == other._priority) {
+			if (_position.y + _z > other._position.y + other._z) {
+				return true;
+			}
+
+			if (_position.y + _z == other._position.y + other._z) {
+				return _object > other._object;
+			}
+		}
+
+		return false;
+	}
+
 	/**
 	 * Calculates the dimensions and scaling parameters for
 	 * the screen item, using the given plane as the parent
@@ -279,12 +297,10 @@ public:
 
 typedef StablePointerArray<ScreenItem, 250> ScreenItemListBase;
 class ScreenItemList : public ScreenItemListBase {
-	inline static bool sortHelper(const ScreenItem *a, const ScreenItem *b) {
-		return *a < *b;
-	}
-public:
-	ScreenItem *_unsorted[250];
+private:
+	size_type _unsorted[250];
 
+public:
 	ScreenItem *findByObject(const reg_t object) const;
 	void sort();
 	void unsort();