Not sure if this is a kwin bug, gtk bug, or geany bug, but I can't change any preferences in geany because the program will eventually crash after opening the Edit>Preferences dialog. High CPU is also reported for kwin.
kwin version 4.11.5
This is on an up-to-date install of Kubuntu 13.10
I believe this must be one of the many bugs of the oxygen-gtk theme used under KDE. This theme gave us tons of reports, like e.g. [#758], both for crashes and CPU usage.
Could you please try with another GTK theme? (assuming you are indeed currently using oxygen-gtk)
Related
Bugs:
#758Ah it seems you're right, it works fine with other themes. Thanks.