Deluge
This is not a huge issue as you can just press cancel and close the Window but I have noticed on 1.3 RC1 and RC2 if I open the preferences Window and then press Ok the window does not always close sometimes you have to just press cancel or the X to exit the window.
I have also noticed on RC2, if I open the preferences Window and browse around a little, if I do this a couple of times the 3rd or 4th time I press the preferences button nothing happens it does not open.