actually most "mouse events" are better done on pure-tcl level, only calling your perl calback when necessary - this is my approach.

but - yes, your approach is also possible, you only must give to tcl/tk an idea that you're waiting for '%x,%y' or '%X,%Y' event variables.

you will have much quicker responces if you'll ask this question to devoted mailing list - tcltk at perl dot org.

regards,
Vadim