It may happen that all of a sudden a window will not close itself if the application behind it is blocked. In this case, click on the shortcut "XKill" and click on the offending window which will definitely disappear.
Furthermore, if you have difficulties in moving a window because it is not completely displayed, right-button click on one of its borders and select "move".
All the KDE programs and their default configuration files can be found in the directory /opt/kde. Each user possesses also his or her own KDE directory in their personal directory. It is the directory ~/.kde (~/ is the path for the personal directory of the user who requests it). The personal configuration of KDE for each user is located in their file ~/.kderc, but normally you will not have to modify this file by hand: use instead the "KDE Control Centre" (in the K menu) which allows you to completely configure your environment!