-mouseDownFlags while dragging over NSCells returns 0

FROM : Roland Torres
DATE : Tue Apr 03 22:28:51 2007

I have a 64x64 NSMatrix of NSCells. I've subclassed NSCell to capture 
the -drawWithFrame:inView: invocations so I can change the color of 
the cells that the user clicks on. This works great.

Now I need to color the cells by clicking and dragging the mouse over 
them (not explicitly clicking on each one, just a downclick on the 
first one, and an upclick on the last one), but I don't know how to 
find out (from within NSCell's -drawWithFrame:inView: method) that 
I'm in a mouse down state. The -mouseDownFlags method returns nonzero 
only when the mouse is downclicked on the first cell, but the other 
cells that get dragged over return 0.

Is there some way to know, when an NSCell's -drawWithFrame:inView: 
method gets invoked, that it's in a mouseDown event?

Roland