I am the developer of this app.
Vill Q just released yesterday. It brings some new fun to work with screen drawing on your Mac. There are some other apps which can do the same thing, but if you use Vill Q, you will love to use it forever, and it brings you some new feelings for drawing on your screen.
BTW, You may ask what's the different between Vill Q and others. I have to point out two key features of Vill Q:
1) Undo/Redo feature
2) You can draw with both your mouse and your Mac's trackpad
3) Every easy-to-use friendly user interface
Of course, I love all of Vill Q, like it's user interface made by hand and heart. :)
Maybe I can not tell you how much I love it, why not just try it out and see if Vill Q is made for you?