Restructuring layout UI of the app to accommodate more tools/painters on screen in minimalistic manner

[claws99]

On #455 you said:

Where do you want this button? I don't want to add too many things on the toolbar

This is going to be a recurring question as the app progresses. With more users, there will be more use cases (right now we are trying to provide only bare minimal features) and there will be more feature requests and more UI elements. And for the user's use-case he/she would want the best UX (which mostly translates to single-click) access for the tool he or she'd need.

This simply means providing more UI elements on screen without cluttering screen. This is especially important on smaller screens.

This is a design decision we need to discuss few possible designs and pick best suited one.

I suggest let's look at how other well established apps solve this issue.