A thought struck me just now. My impression is that a lot of applications, when resized, will just resize the widgets, UI, toolwindows, everything with it in a proportional manner. Wouldn’t it be better if when you resize, the less important widgets and window elements are just hidden, and pop up again once you enlarge the window and give it a bit more screenspace?
How about a way to prioritize the elements on screen, such that you can define some things as always-needed (kind of like always on top in window manager space), and rank other less important tools below that. My vision is then, that for example an app like Krita, once you make the app really small it would only show the bare necessity, in this case somethinglike just the picture and a color chooser.
A picture I made with my awesome gimp skills for those of you that cannot see my vision through my words: