Why can't I get the cursor to stay put for the duration of my mouse drag? As soon as I start dragging, it reverts to "Arrow" (even though I set it as open hand in the app delegate after launch).

```
- (void)mouseDown:(NSEvent *)event
{
   [[NSCursor closedHandCursor] push];
}

- (void)mouseUp:(NSEvent *)event
{
   [NSCursor pop];
}

```