bug#51782: 28.0.60; Certain popup menus don't respect margin

[Po Lu]

On X, go to an Info buffer with `left-margin-width' set to, for example,
50.  Then make sure the margin is actually updated in the window
displaying the Info buffer (such as by calling `set-window-buffer').

Any C-down-mouse-3 will display a menu offset to the left by
`left-margin-width' from where it should actually be.