Do you need the exact changes made or do you only care about the final state? If the latter, you could simply read back the Listbox contents after the $int->Eval(); returns and call a Perl handler there.

In reply to Re^3: Tk programmatically monitor change in Listbox by jcb
in thread Tk (Tcl::Tk) programmatically monitor change in Listbox by IB2017

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