Yesterday i tried again with the program and noticed that the problems occur when in fullscreen. Under workbench appears to be all ok. Also, in order to save the data in the addressbook, clicking on ok with the mouse isn't enough and you have to push enter after every entry. If you don't terminate every entry with enter, the data isn't saved.
All in all, for now it serves it purposes, but i would like to know if there is some way to minimize these problems.