PNG image following cursor, over a Tk canvas.
FROM: http://wiki.tcl.tk/864
(imaged on 2009 mar 19)

Tk doesn't seem to directly support using PNG cursors or XPM cursors.
However I found a way around this by having an image follow the
cursor around. The window cursor is set to a blank.xbm. Which is
simply a bitmap created with the bitmap program with only a hotspot
defined. The PNG image follows the invisble cursor around.

(I have a mouse cursor position setup screen in my game to make
it accurate. My setup screen is a square that has bindings for enter
and leave that cause the cursor to be displayed. I have a scale on
the bottom and side that allows adjusting the amount to subtract or
add to the pointerx and pointery values.)

Here is an example:

--------------------

 #! /usr/bin/env wish

 package require Img

 set can .frame.can
 frame .frame
 pack .frame

 canvas $can -width 30c -height 22c
 pack $can

 set default_cursor_image [image create photo -file ./cursor.png]

 bind . <Motion> {cursor_move  %x %y}
 . configure -cursor "@blank.xbm black"

 proc cursor_move {x y} {
     global default_cursor_image can

     #Try removing this if you want to draw some fun pictures.
     catch {$can delete default_cursor}

     set x [$can canvasx $x]
     set y [$can canvasy $y]

     $can create image $x $y -image $default_cursor_image -tag default_cursor
 }

-----------------
END OF SAMPLE CODE.

GPS: I wrote that cursor code many years ago. I think we could
make the cursor code faster, by not recreating the image.