When I couldn't find a solution I have lastly uninstalled 1.7.12 version, downloaded 1.9 version from here and installed it (Thanx to TheDuke). Problem solved with new version.
In new version, you can even adjust width of panes by sliding middle bar in a dialog box, it is a good feature.
Edit: I still have same problem in some dialogs that don't have this feature like in the picture
Why is this happenning? Is it about graphic card or what?
