Main groups in left pane should be collapsible
The very few times I use this app I always end up scrolling down to math symbols. That is what I use, and everything above is just noise. It would be a help if I somehow could collapse groups I don't need, or very seldom use, like the emojis. The entry for recently used is a help, but if I already have the symbol I usually just copy-paste.
If the left pane was a collapsible list (or tree) I would prefer the hierarchy to follow the established unicode groups, perhaps with entries from all subgroups shown in the parent group unless drilled down to the subgroup itself. It would then look (almost) like it is now unless the user navigates down into the hierarchy.