Code review comment for lp:~tapaal-contributor/tapaal/undo-redo-not-available-when-drawing-arc-1848949

Yes, it compiles and works nicely on mac as well, when I press ctrl-z then only the arc disappears.
However, if I press in the GUI on the back-arrow in the tool line (instead of ctrl-z), then also the place disappears, which is not the same behaviour as intended.