Imo there could a lot be done in terms of design. I dislike that there are some big vertical paddings e.g. on the tabs, which lead to fewer screen real estate. Being able to adjust those along with the icons etc. would be quite cool. Same goes for themes in general and the settings for PL/SQL Developer e.g. editor background, font colors etc. They are kinda squished together with other preferences. Would be cool to have those isolate and being able to share themes etc. pp.