Its menu contains an 'Add-Remove Software' GUI tool, which seems to be a thin and ill-conceived wrapper around apt-get (?). It combines several horrible choices, which conflict and clash perfectly. (1) it appears to insist on retrieving and building its entire list of apt packages, EVERY TIME YOU TRY TO OPEN OR OPERATE IT. (2) it doesn't give you any choice to CACHE this data, or any choice to skip this "refresh". (3) it takes five minutes or more to refresh this list, on our raspberry 3. (4) on any excuse you give it, it will refresh the list again. (5) once it succeeds in retrieving this insane 5-minute list, it presents it to you in an unnavigable manner - no sorting, no searching, no filtering, just a scrolling list with something like 10.000 apt packages.. page up/page down doesn't seem to work. For example, I naively pressed the cursor keys, wrongly assuming it would move my selection point in the 10.000+ list.. WRONG: Instead, it navigated a category-word-list, causing it to redo the 5-minute re-init. In effect, it because a 'trial and error game from hell', where you can attempt 10 wrong ways to navigate the list, each time being punished with a 5-minute "no you can no longer view the list you just waited 5 minutes to retrieve, you must now wait 5 minutes again for your next wrong attempt!" (6) oh yeah, and you are not allowed to view the partial list during load. I really really wonder who decided to implement that window in that maddening way??
In the end, I resorted to using apt search in the command line, which of course works perfectly, but not before having wasted about an hour together with my less-tech-savvy dad, trying to make the raspian package install UI "work" in the naive idea it would be easier for him to use :-/.