[jezek2]

This has been tried, even in the browser. It just leads to buttons that do nothing when clicked, scrolling to unpopulated areas, infinite loading animations and other such artifacts.

It does not help, you have smooth animations but you feel you're disconnected from the program and trust it less. The UI code just needs to not take much time and offload background stuff to another thread, but not the UI logic itself. It also naturally synchronizes events.

And sometimes it's better to briefly block UI thread as the alternatives lead to worse user experience.

[vbezhenar]

I still feel these issues could be solved one by one.

Button click will automatically disable it, until its handler executed. There could be creative animations translating this state to the user in an intuitive way, so the button does not feel stuck and does not feel doing nothing.

Scroll widget should require some placeholder graphics which will be displayed until loading handler executed and replaced this placeholder with real data. A lot of apps already do exactly that.