Over the years, quite a few graph editors seem to have been written in Tcl/Tk (the canvas probably has something to do with this). This page is for listing such applications and related material.
Lars H remembers downloading a graph editor of French origin once, but cannot recall its name, only that it came as a tclkit. (It's possibly the app described on http://wfr.tcl.tk/208 , but the download link there doesn't work anymore.)