This patch by @Massimo attempts to solve issues #4713 (closed) and #9489 (closed).
Currently, clicking on an item below the scrolled window in Preferences -> Toolbox causes the window to autoscroll to the first entry. This is because focus is grabbed before the click specifies which item you selected, so it defaults to the first item. Massimo suggested that the grab focus code be removed to resolve the issue.
I have tested the fix with master and it works as described. My only concern is if there's some interaction I'm missing that wouldn't cause the widget to already be focused when clicked. @Jehan, I saw that you edited that line a few years ago to add an additional restriction. If you have time, is there any reason it shouldn't be removed entirely per Massimo? Thanks!