What does this TCL/Tk code do?

Question

I found this pie menu code for TCL/Tk here: http://wiki.tcl.tk/15400

There is a line of code I don't understand:

-command0 {bind .c <Button-1> {}; %W delete __pm; incr cnt} \

What does it mean? I think this happens: the global variable cnt is incremented. All items with the tag __pm will be removed from the canvas. This all happens if the mouse button is clicked. But this doesn't really make sense does it?

Answer 1

It makes sense if you actually run the demo, which demonstrates pie menus with a varying number of buttons. Clicking the central "button" labelled "Ok" will delete the pie menu. Note that this central text element is item 0. %W is short-hand for the pathname of the window relating to the Tk event that fired. Incrementing the cnt (count) will cause the next pie menu to be created to have a different number of "button" elements.