Click to begin shape, click again to end
c: circle mode
r: rectangle mode
l: line mode
f: free draw mode
s: continuous shape, double click to exit
1-9: sets thickness
+, -: increases/decreases thickness by 2
up and down arrows: rotates through pen colors
shift + up and down arrows: rotates through background colors
left arrow: undo
space: clears canvas
ctrl + s: download drawing (png)