Currently, the "User account & password" KCM refuses to change the user image if KDM is set up not to use user images. That however does not make much sense, all this applet does is writing the image to ~/.face.icon, which the user can do manually anyway. The fact that KDM might or might not actually display this image in the user selection is unrelated, as KDM is not even the only user of this file: Plasma Kickoff displays it, and maybe more apps use it (GDM uses a different file, though)

This patch therefore removes the check for the KDM settings and makes the KCM simply manage the .face.icon file. It does not fall back to the system default if the user image does not exist, as Plasma Kickoff does not do that either. The patch also adds a button in the "Change face" dialogue to remove the user image, to make it possible to go back to the default state again.

After changing the image, the user still has to log off and on again for Plasma to use it - Plasma would have to somehow listen to changes to that file. I don't know if that is desired.

Compiled and verified that the KCM now behaves as desired.