How about tips when people press a button telling what each thing does and tips on different ways of doing things.
I’m not sure about it…
I don’t think it’s a bad idea, but I’d recommend per-tool “tooltips” for minimum space invasion, also maybe not a button but a (rebindable) keyboard shortcut to enhance said tooltips.
For example Zbrush, the 3D scultping app has this feature. When you pass the cursor over a tool it gives you a short description of the tool’s function, but when you press ctrl the tooltips expand to a larger and more precise description of how to use the tool and what it does, with images on the tooltip.
Of course Zbrush is more robust than Pencil at the moment, and it needs more exposition, but inside Pencil2D it could help beginner’s to get acquainted to the tools faster and to see their less obvious and “hidden” functions which have been mentioned in the past.
The tooltips could parse the central Pencil help file which could be a formatted XML file that could be easily updated, having those tooltips update on their own as well. I imagine we’d have to write sort of a “tooltip” viewer on top of the pencil app, but if we get a plugin manager as I think @feeef suggested for a future time, maybe this isn’t as impossible as it sounds.