Tkinter canvas drag/drop obstacle

[Peter Pearson]

Tkinter makes it very easy to drag jpeg images around on a
canvas, but I would like to have a "target" change color when
the cursor dragging an image passes over it.  I seem to be
blocked by the fact that the callbacks that might tell the
target that the mouse has entered it (<Enter>, <Any-Enter>,
even <Motion>) aren't called if the mouse's button is down.
What am I missing?  Have I failed to find the right Tkinter
document?  Is Tkinter the wrong tool for this job?  Thanks.

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