seems like the canvas gadget behaves itself now with regards the mouse up event in that it fires even outside of the control (once the mouse down has been registered of course).
Also, mouse down will not fire if you click in a hidden part of the control (e.g. if the canvas gadget is embedded within a container).
Seems like a massive improvement. Will keep testing though.
**EDIT : ok, the mouse move event still registers even when the mouse is not down and the cursor is over a hidden part of the control. Not a major problem though as you will usually record the fact that the mouse is down anyhow and this seems to work fine. Will post a bug report nevertheless.