Canvas -- a sub-panel of the screen
X,Y coordinate system
Canvas properties: Width, Height, BackgroundColor, PaintColor
Canvas functions: DrawCircle, DrawLine
note that dragged is triggered many times as user drags finger across the screen
Demo: Show x,y coordinates in a label when you touch canvas
Set the width of the canvas to "Fill parent"
note that event parameters are found in My Blocks (don't grab from event)
How to draw a circle in middle of canvas?