[bugfix] Canvasdraw : correct previous commit, as touch identifier is a SIGNED int, so it can also be < 0 ==> replace evt.identifier >= 0 by typeof(evt.identifier) != 'undefined'
+ continue Replacing non standard "which" by "button" (see https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/button :
* evt.which == 3 by evt.button == 2
* evt.which == 1 by evt.button == 0