This will make it behave like Safari: the source window will hide during
drag and the miniwindow will appear
308c308,309
< #warning fix me - what should we do when the last tab is dragged as a
miniwindow?
---
> [_draggedTab switchImages];
> _centersDragWindows = YES;
505c506,508
< [[_draggedTab window] setAlphaValue:0.0];
---
> if ([_sourceTabBar tearOffStyle] == PSMTabBarTearOffAlphaWindow) {
> [[_draggedTab window] setAlphaValue:0.0];
> }