"Keep aspect ratio" button for any attribute of Width and Height
it should be a button implemented everywhere for Width and Height slider, to enable or disable "maintain aspect ratio".
Most attributes need proportional scale and it takes a lot time, always to adjust both sliders.
Furthermore, if you want a quick comparison "before-after", you never can see it, because either the viewer has already updated.
you have to wait unnecessary minutes, for example when you change in absolute values the output size of your material.
I had the situation, that I needed to wait 3 minutes after sliding from 256px to 4096px in Width, and then only I could adjust Height, with again 3 minutes waiting time.
This is at the moment only integrated in Parent size toolbar, but should be available everywhere and also for absoulte values of Outputs.