Custom Toolbar
As the drawing tools get more flexible, I'm finding I have to do a lot of clicking to move between brush selection and brush settings.
A custom toolbar would be great, allowing you to drag the current brush, with all its settings, onto a floating toolbar and then have that brush available at a single click. So you could have, for instance, a soft pencil, a hard pancil, a large transparent eraser and a small detail eraser all instantly available without having repeatedly to move back and forth between brush selection and settings.
I was sure I replied to this before.Anyway I do like the idea of custom toolbar for frequent use tools.Infinite Paint has this feature which you basically go to a page of tools,click and hold and then drag to the toolbar area.Once you have done this the tools stay there for everytime you run the app(in it's early implementation you had to do it every time but they fixed that).
Also OT, scrollable tool bars can be handy as long as there is a good indicator that it does scroll (some apps I have accidently discovered the toolbar scrolled).