The position of the submenu initiated by the tab key is incorrect

When the main menu is on the right edge of the screen, the position of the submenu triggered by the tab key is far away from the main menu, which is very unfriendly. According to the code， the position of the submenu is the position of the mouse, it should take the position of the left edge of the main menu。User the  customize style in the attached  example (menu-test).