There is no easy way to solve this issue, because when menu opens, the fullscreen overlay apllies too. The overlay is intended to detect click, then close menu and remove the overlay. As you already guessed, this overlay prevent clicks on another menu trigger and we can't open the menu, when another one is already opened.
As a workaround you can do something like this:
Catch click event on the overlay, get x
and y
axis, and after the overlay will be removed, you can check, does user want to click on another menu (you can use method from this post), and if so, simulate another one click at the same axis.
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