On a related note, there is a spirit level in one of the apps we've done:
and the original mock-up of this was two panels - the body was a long panel say 600 x 100 pixels with mildly-rounded corners, and the bubble was a say 96 x 96 pixel panel with corner radius 48 so that it was actually a circle, and could be moved left and right by changing BubblePanel.Left = horizontal position.
But now I can't find the mockup project... maybe I didn't save an separate copy, might have just moved on to using the spirit bubble and body images shown above.