Drag and drop onto cells?
 

I am trying to figure out how to get events for drag and drop onto a
worksheet, so that for instance you can have a form with an icon (just for
example) that you drop onto a cell on the worksheet to "make something
happen". It seems that I'd need to get an event from Excel that says
"someone just dropped something on cell $N$34" - but after scouring the docs
I don't see anything like this. I've seen a commercial application that
implements this feature - did they hook the Windows API and calculate the
cell boundaries somehow - or is there a reasonable way to do this?

Thanks in advance,

Joel