Kdevelop doesn't show the editor window

Question

I'm trying to open a project file in the main editor of kdevelop, but it is not able to show it. I have tried also with a new file, but still the same. It seems that there is a window separator in the middle of the grey window.

I have remove the project, purge and reinstall the application but it doesn't work. The Editor menu in the tools bar doesn't have nothing inside.

I'm using kubunu 11.10, KDE 4.7.3 and KDevelop 4.2.3

Does anybody had this problem?