Problem:
When using floating panel applets with Focus Follows Mouse, panel applets become extremely difficult to interact with.
When I click a panel applet, it pops up — but as I move my mouse toward it, the cursor briefly passes over the small gap between the panel and the applet. Plasma then shifts focus away (to the desktop or another window beneath the gap), and the applet instantly disappears.
This makes using floating panel applets frustrating — I basically have to play Tom and Jerry, moving the cursor within milliseconds to where the applet will appear, just to keep it focused.
Proposed Solution:
Panel applets should not lose focus when the pointer moves away, even if Focus Follows Mouse is enabled. They should only disappear when the user clicks outside the applet or presses the Escape key. I believe GNOME behaves this way already.