I'd add evil enemy, although the change seemed to be done with good intentions. I used to run four desktops with cranky old engineering applications, including matlab, in each one. Then I updated RHEL and got thrown into a focus stealing hell. Blinking items were appearing on the current taskbar from another desktop. My taskbars were already full and organized and this meant that to restore my organization, I had to go service some app on another desktop and return. Over and over, many times per hour. KDE could disable it once I could name what was happening to me, but KDE has a little windowing delay that randomly messes with my main application being able to pop a window . The application isn't going to adapt so KDE was out.
I use IceWM for vnc sessions of the same setup and updated to the (then) latest version, thinking that I'd get some new and useful feature, and it did the same darn thing. I reverted to the old IceWM and would have stayed forever at that version as it was my only useful solution. Then life took a left turn and here I am lurking Slashdot. Focus stealing is not my main issue today.