Opened application menu does not close when clicking icon
On a horizontal top panel, the application menu opens a pull-down menu when its icon is clicked. Depending on the horizontal position of the application menu (distance to left edge of the screen) the pull-down menu is aligned horizontally to the position of the icon either with its left or with its right menu edge. In the latter case, clicking the icon again makes the pull-down menu close (which I regard as the correct, desired behavior). Remark: you probably need to configure the title not to be displayed in order to achieve this.
However, when the pull-down menu is aligned to the icon's position with its left border (because it is placed sufficiently distant to the left from the right screen edge) clicking the icon again does not have an effect (once the pull-down menu has been opened). I consider this a bug.
This bug does not occur when the application menu is put in a bottom panel and consequently uses a pull-up menu.