Using SlickEdit Pro x64 (23.0.0).
1. I turn "Show preview of symbols in tool windows on mouse-over" OFF, so that I can CHOOSE what's displayed in the preview window by clicking on a Ref/Def and be able to freely move my mouse afterwards (how isn't this the default?); anyways, the bug is that the "Show preview of symbols in tool windows on mouse-over after (ms)" value (which is grayed-out) still affects the behavior of when the preview window updates after clicking a Ref/Def!
2. Like I said above, I have "Show preview of symbols in tool windows on mouse-over" OFF so that I'm free to select an item from Ref or Def and view it in the Preview window (without the fear that moving my mouse will change what's displayed in the Preview window), BUT if you select a new item in Refs or Defs and then shift your mouse off the item the Preview window will go back to displaying some prior area (like a Ref/Def you had previously selected). Messed with multiple timing settings and behavior is very inconsistent. If you "click" "wait" "click" then there's a better chance that the Preview window stays previewing the selected item (but it's not assured). If the first try didn't work (preview window shifted back to previewing a prior item), then the second try will work (preview window stays previewing selected item). This is just overall annoying (since Defs doesn't have it's own preview window like Refs does).
3. When SlickEdit loses focus the Preview window goes back to showing whatever you had selected in the Editor window (I can live with this, but #2 has been a constant source of frustration for a long time now).
Note: These happen with background tagging on or off