SCI32: Always sort kernel-generated screen items above script-generat…

…ed screen items in last-ditch sort

Fixes Trac#10257. Fixes Trac#10261.

engines/sci/graphics/screen_item32.h

@@ -256,6 +256,16 @@ class ScreenItem {
 			}
 
 			if (_position.y + _z == other._position.y + other._z) {
+				// Synthetic object IDs (numeric IDs) are used for screen items
+				// generated by the kernel, like the screen items generated by
+				// plane pics. In SSCI, these synthetic IDs started at 20000 so
+				// would deterministically always sort higher than any
+				// script-generated view in SSCI at the same position and
+				// priority.
+				if (other._object.isNumber() && !_object.isNumber()) {
+					return true;
+				}
+
 				// SSCI's last resort comparison here is to compare the _object
 				// IDs, but this is wrong and randomly breaks (at least):
 				//
@@ -295,6 +305,10 @@ class ScreenItem {
 			}
 
 			if (_position.y + _z == other._position.y + other._z) {
+				if (_object.isNumber() && !other._object.isNumber()) {
+					return true;
+				}
+
 				// This is different than SSCI; see ScreenItem::operator< for an
 				// explanation
 				return _creationId > other._creationId;
@@ -310,6 +324,10 @@ class ScreenItem {
 		}
 
 		if (_priority == other._priority) {
+			if (_object.isNumber() && !other._object.isNumber()) {
+				return true;
+			}
+
 			// This is different than SSCI; see ScreenItem::operator< for an
 			// explanation
 			return _creationId > other._creationId;