set-label in labelled-menu-item<%>
Sets the menu item's label. If the item has a shortcut, the shortcut is not affected.
If the label contains an ampersand (``&'') and the window is a
control, the label is parsed specially; under Windows and X, the
character following an ampersand is underlined in the displayed menu
to indicate a keyboard mnemonic. Pressing the Alt key with an
underlined character from a menu's name in the menu bar causes the
menu to be selected (via on-menu-char). When
a menu has the focus, the mnemonic characters are used for navigation
without Alt. A double-ampersand in the label is replaced by a literal
(non-navigation) ampersand. Under Mac OS X, ampersands in the
label are parsed in the same way as for X and Windows, but no
mnemonic underline is displayed.
An ampersand is always preserved in the label returned by
get-label, but never preserved in the label returned by
get-plain-label.
For historical reasons, if a label contains a tab character, then the tab and all remaining characters are hidden in the displayed menu.