cantSelect and graphics

[Graham Samuel]

I think the following is true for a desktop app:

If a the graphic drawing tool is chosen, the user can't draw the graphic if the drawing begins (the initial mouse down is positioned) on an object whose cantSelect is set to true: for example, if there is a rectangle with cantSelect set to true, you can't draw a new rectangle starting exactly on one of the lines of the original one, even though the new graphic is clearly on a higher layer than the original; and if the original one is opaque, you can't draw within the original one's rect at all. 

This has some very odd consequences for drawing apps where some kind of non-selectable background exists, such as axes for a graph-drawing program: in such a case you can't start drawing on the exact line of either of the (non-selectable) axes. There may be a workaround but the LC dictionary doesn't tell you what is.

Am I right about this, and is there a workaround? I think if there is, it's something to do with 'mouseDown'...

TIA

Graham