On Explorer for clicks on menubar:
Pressing alt and then mouse click opens the clicked menu, if there is second mouse click, it hides the accelerators and opens the clicked menu. If the second click is on the same menuitem the accelerators are gone and the menu is closed.
The above was for clicks outside the menubar.
On Explorer for clicks on menubar:
Pressing alt and then mouse click opens the clicked menu, if there is second mouse click, it hides the accelerators and opens the clicked menu. If the second click is on the same menuitem the accelerators are gone and the menu is closed.