In Cream 0.34 (and earlier versions -- I'm unsure when I first noticed this behaviour) when I have two files open in a split horizontal window and have them in diff mode, when I click on the window that is not in current focus, spurious characters are inserted at the point where I click. Six examples from six different clicks follow:
Subsequent clicks in the same window do not paste these spurious characters. Also, it is not sufficient to merely have two files open in split windows to reproduce the bug. The files must be in diff mode.
When I close one of the files or take one window out of diff mode, the problem stops.
Use <ctrl>-<tab> to switch between windows.