Editing groups

[Simon Lord]

I'd like to use a group as a mask object.  That way when objects are 
dragged they are clipped at the edge of the group unlike the current 
situation whereby the object can be dragged willy nilly over the 
interface.

My question is how can we choose the image tool and draw an image in 
the group during runtime?  I remember doing this years ago but have 
since lost that stack.

Sincerely,
Simon