If I leave my system alone for a while the screen saver starts (normal)

and a few unexpected things happen:
  1. Some windows move from one desktop to another, generally it's
     Konsole (KDE's console) that moves from its normal place, desktop 1
     to cover Chrome on desktop 4.  Other windows may also move,
     generally to desktop 4.
  2. Some winndows become larger, and start to go under the panel.  
     They may also start to expand off the screen horizontally, generally  
     to the right.   

Has anyone else seen anything like this?  Any idea what's going on?

The system is:
     4-processor x86_64 hardware
     Fedora-23
     KDE
     All updates are installed