A bug likely exists in CTTabWindowController

[enloyee]

Hi!

There may be a bug in setUserOverlay: method of CTTabWindowController.

I always got an exception while dragging a tab to another window for merging them. I hacked
your code, and found that it was caused by [window makeFirstResponder:cachedContentView_].

In apple's document, they said that
"If this method is called explicitly, first send acceptsFirstResponder to responder, and do not call
makeFirstResponder: if acceptsFirstResponder returns NO."

But I am not so sure about this, and please make your own decision.

Best regards.