pop char like on a macintosh

One of the best features of a macintosh is a little
utility called PopCharLite: a little icon (a P) is
displayed in the top left corner, and when you click on
it, all ISO characters appear, and you select one that
is pasted into the text field you where just typing in.
This is especially great for weird characters (like the
"SCHARFES S" in German, or all the accents in some
langagues, omega, alpha, diameter, ...).

This is not exactly a IceWM only feature request, since
it should be written for X. considering how the 3-rd
button works in X, this utility should not be too hard
to write.

Anyway, this would be a killer-app.

It would be great if someone took the task.

Ciao