macosx: re-write the resize control used in the black window style to use the...

macosx: re-write the resize control used in the black window style to use the MouseDown event instead of the MouseDragged event which is ignored on Leopard (should fix #5822)
(cherry picked from commit f2a677c0)

modules/gui/macosx/MainWindowTitle.m

@@ -271,8 +271,16 @@
 
 @implementation VLCResizeControl
 
-- (void)mouseDragged:(NSEvent *)theEvent
-{
+- (void)mouseDown:(NSEvent *)theEvent {
+    BOOL keepOn = YES;
+
+    while (keepOn) {
+        theEvent = [[self window] nextEventMatchingMask: NSLeftMouseUpMask |
+                    NSLeftMouseDraggedMask];
+
+        switch ([theEvent type]) {
+            case NSLeftMouseDragged:
+            {
                 NSRect windowFrame = [[self window] frame];
                 CGFloat deltaX, deltaY, oldOriginY;
                 deltaX = [theEvent deltaX];
@@ -294,6 +302,20 @@
                 }
 
                 [[self window] setFrame: windowFrame display: YES animate: NO];
+                break;
+            }
+                break;
+            case NSLeftMouseUp:
+                keepOn = NO;
+                break;
+            default:
+                /* Ignore any other kind of event. */
+                break;
+        }
+
+    };
+
+    return;
 }
 
 @end