http://bugs.winehq.org/show_bug.cgi?id=58096
--- Comment #1 from wine_bugzilla@sctb.ch ---
My suspicion here is that I might be issuing from the mouse a very rapid *triple* click, and there's some kind of race condition, where the third click is causing the observed behavour; and that this is why it happens *sometimes* only.
It is not this; the same problem occurs with my touchpad.