Ok, I see now this is taken care in canvas_doclick, which can set the cursor to "resize" in some cases. Things seem to be clearer now to me. 

But I also see now that it's all quite hard coded into Pd and impossible to expand it to externals. A GUI external could benefit from setting another cursor, such as "bottom_side" for a custom dropmenu button, or "plus" to tell you that you can add a segment into an envelope generator, etc.

Using the canvas_setcursor function into a w_clickfn call doesn't work to override the cursor. I can't think of a simple solution like I did by suggesting a new "edit" message in my last email. Nonetheless, I think this would be a nice feature that it's worth discussing.

cheers