Ok, I've earned my "expert" wings but only have 255 points so far, but I'll happily give them all away to anyone who can drop their inhibitions for long enough to tell me why I'm having this problem - and preferably suggest a work-around within the same context!
I've successfully subclassed an Excel spreadsheet in the project posted in the following link, which facilitates a mouse-tracking tool. Very handy (if you like that sort of thing) - however as explained in the thread, mouse-clicks are subsequently not received by the worksheet window.
ps. Sorry if the points seem stingy, I've been wating for a month and it's all I've got but I'll happily write an IOU for 500! :)