Unfortunately, just adding the binding to <button-2> does not work because the Tk Text widget already has a documented binding of "paste-text" to <button-2> and this does not override that.  With the binding added, I found that the button-2 behavior for breakpoints did not work correctly as both events would be triggered and the resulting breakpoint lines were incorrect.  That, plus the compatibility issue, is why I thought it best to just stick to control-click.