Mac: cmd + pressing the oblong button makes the toolbar resize wrongly

On Mac cmd + pressing the oblong button makes the toolbar resize wrongly.

It can be seen for example in assistant or the macmainwindow demo application.

When cmd + pressing the oblong button, that hides the toolbar, quickly many times it is possible to get the toolbar resized to some arbitrary small size, so that the toolbar buttons are not properly shown. When the toolbar reaches this state, clicking the oblong button without the command button pressed will show and hide a toolbar that is perhaps only half the normal size possibly without any buttons in the toolbar showing.