winemac: When ordering sibling child windows, don't remove and re-add ones…

dlls/winemac.drv/cocoa_window.m

@@ -875,7 +875,8 @@ static inline void fix_generic_modifiers_by_device(NSUInteger* modifiers)
     {
         NSMutableArray* windowNumbers;
         NSNumber* childWindowNumber;
-        NSUInteger otherIndex;
+        NSUInteger otherIndex, limit;
+        NSArray* origChildren;
         NSMutableArray* children;
 
         // Get the z-order from the window server and modify it to reflect the
@@ -888,7 +889,8 @@ static inline void fix_generic_modifiers_by_device(NSUInteger* modifiers)
 
         // Get our child windows and sort them in the reverse of the desired
         // z-order (back-to-front).
-        children = [[[self childWindows] mutableCopy] autorelease];
+        origChildren = [self childWindows];
+        children = [[origChildren mutableCopy] autorelease];
         [children sortWithOptions:NSSortStable
                   usingComparator:^NSComparisonResult(id obj1, id obj2){
             NSNumber* window1Number = [NSNumber numberWithInteger:[obj1 windowNumber]];
@@ -912,6 +914,16 @@ static inline void fix_generic_modifiers_by_device(NSUInteger* modifiers)
             return NSOrderedSame;
         }];
 
+        // If the current and desired children arrays match up to a point, leave
+        // those matching children alone.
+        limit = MIN([origChildren count], [children count]);
+        for (otherIndex = 0; otherIndex < limit; otherIndex++)
+        {
+            if ([origChildren objectAtIndex:otherIndex] != [children objectAtIndex:otherIndex])
+                break;
+        }
+        [children removeObjectsInRange:NSMakeRange(0, otherIndex)];
+
         // Remove all of the child windows and re-add them back-to-front so they
         // are in the desired order.
         for (other in children)