When I close the window it reopens but seems to be trashed - button disappears or is not responsive and resizing window to smaller reveals that refreshed areas are painted as if there were no ctrls there. Uncomment the line with prompt and it works as expected - you get a prompt first and when window reopens it is fully operational. Tested on svn version 7404.
I believe this is not desirable behavior, but maybe I should give window a rest and not instantly reopen it like that?