As you all have figured out I'm very new to Tcl/Tlk. I was assigned the hard task to fix a couple of bugs in a Tcl/Tk GUI implemented by someone else. The existent GUI allows for left-button clicking on a color-coded particles flux representation. The numeric value of the flux is correctly displayed on a Point info widget. But for values greater than 10^9 (1e9) an error message pops up on the screen which reads: "Error in Tcl Script Error: integer value too large to represent. OK Skip Messages Stack Trace" If I click on the Stack Trace button I get the following info that I cannot quite understand: integer value too large to represent while executing "expr $num-int($num)" (procedure "format_vis" line 29) invoked from within "format_vis $hst_id """ (procedure "show_info_frame" line 106) invoked from within "show_info_frame 304 335" (command bound to event) In fact the package I'm testing includes a module named "mf.tcl" which is a sequential collection of procs. There is indeed the following boud proc: bind $base.canvas_field <Button-1> {show_info_frame %x %y} proc show_info_frame { h v } { **** Question: **** Is the 106 indicated in the Stack Trace an offset inside the proc show_info_frame ? The proc show_info_frame is at line 1558 of the "mf.tcl" file. If I add ( 1558 + 106) = 1664 which is a line inside the proc show_info_frame but such a proc is NOT recursive. I mean it doesn't call itself. Infact at line 1664 there is the following statement: if { $plot(info_frame) == "" } { There is indeed an "info_frame" but it's not a call to proc show_info_frame. I would appreciate if someone could help me interpret the information provided in the Stack Trace with the hope that helps me find and fix the bug. Thank you in advance for your help, Maura