More Guidebook menu_* settings

Previous update added one change to Guidebook.tex which was omitted
from Guidebook.mn, so catch up.

Don't try to list the interfaces or ports which support each menu
command key.  Just have a generic "not every command is implemented
by every interface" instead.

Flesh out the one sentence menu_search description.

Update an example which shows changing menu_first_page to '{' now
that '{' has a default use for something else (menu_shift_left).
Since 'menu_first_page:^' is the opposite of 'menu_last_page:|' and
'\' shares the same key as '|' with opposite shift state, switch
the example to 'menu_first_page:\'.

doc/Guidebook.mn

@@ -3796,15 +3796,12 @@ Partial skips the object class filtering and
 immediately displays a menu of all objects.
 .lp menu_deselect_all
 Key to deselect all items in a menu.
-Implemented by the Amiga, Gem, X11 and tty ports.
 Default \(oq\-\(cq.
 .lp menu_deselect_page
 Key to deselect all items on this page of a menu.
-Implemented by the Amiga, Gem and tty ports.
 Default \(oq\\\(cq.
 .lp menu_first_page
 Key to jump to the first page in a menu.
-Implemented by the Amiga, Gem and tty ports.
 Default \(oq\(ha\(cq.
 .lp menu_headings
 Controls how the headings in a menu are highlighted.
@@ -3813,19 +3810,15 @@ Values are \(lqnone\(rq, \(lqbold\(rq, \(lqdim\(rq, \(lqunderline\(rq,
 Not all ports can actually display all types.
 .lp menu_invert_all
 Key to invert all items in a menu.
-Implemented by the Amiga, Gem, X11 and tty ports.
 Default \(oq@\(cq.
 .lp menu_invert_page
 Key to invert all items on this page of a menu.
-Implemented by the Amiga, Gem and tty ports.
 Default \(oq\(ti\(cq. \" ~
 .lp menu_last_page
 Key to jump to the last page in a menu.
-Implemented by the Amiga, Gem and tty ports.
 Default \(oq|\(cq.
 .lp menu_next_page
 Key to go to the next menu page.
-Implemented by the Amiga, Gem and tty ports.
 Default \(oq>\(cq.
 .lp menu_objsyms
 Show object symbols in menu headings in menus where
@@ -3836,19 +3829,15 @@ menus to the right edge of the screen. Only for the tty port.
 (default on)
 .lp menu_previous_page
 Key to go to the previous menu page.
-Implemented by the Amiga, Gem and tty ports.
 Default \(oq<\(cq.
 .lp menu_search
-Key to search for a menu item.
+Key to search for some text and toggle selection state of matching menu items.
-Implemented by the Amiga, Gem, X11 and tty ports.
 Default \(oq:\(cq.
 .lp menu_select_all
 Key to select all items in a menu.
-Implemented by the Amiga, Gem, X11 and tty ports.
 Default \(oq.\(cq.
 .lp menu_select_page
 Key to select all items on this page of a menu.
-Implemented by the Amiga, Gem and tty ports.
 Default \(oq,\(cq.
 .lp menu_shift_left
 Key to scroll a menu\(emone which has been
@@ -4713,7 +4702,7 @@ For example:
 .sd
 .si
 BIND=\(haX:getpos.autodescribe
-BIND={:menu_first_page
+BIND=\\:menu_first_page
 BIND=v:loot
 .ei
 .ed
@@ -4725,7 +4714,8 @@ You can also bind the \(lq<esc>\(rq, \(lq<enter>\(rq, and \(lq<space>\(rq keys.
 .lp "Menu accelerator keys"
 The menu control or accelerator keys can also be rebound via OPTIONS lines
 in the configuration file.
-You cannot bind object symbols into menu accelerators.
+You cannot bind object symbols or selection letters into menu accelerators.
+Some interfaces only support some of the menu accelerators.
 .lp "Special command keys"
 Below are the special commands you can rebind.
 Some of them can be bound to

doc/Guidebook.tex

@@ -4152,7 +4152,6 @@ Implemented by the Amiga, Gem and tty ports.
 Default `\verb+<+'.
 \item[\ib{menu\verb+_+search}]
 Key to search for a menu item.
-Implemented by the Amiga, Gem, X11 and tty ports.
 Default `:'.
 \item[\ib{menu\verb+_+select\verb+_+all}]
 Key to select all items in a menu.
@@ -5165,7 +5164,7 @@ For example:
 
 \begin{verbatim}
     BIND=^X:getpos.autodescribe
-    BIND={:menu_first_page
+    BIND=\:menu_first_page
     BIND=v:loot
 \end{verbatim}
 
@@ -5181,6 +5180,7 @@ the ``{\tt <esc>}'', ``{\tt <enter>}'', and ``{\tt <space>}'' keys.
 The menu control or accelerator keys can also be rebound via OPTIONS lines
 in the configuration file.
 You cannot bind object symbols or selection letters into menu accelerators.
+Some interfaces only support some of the menu accelerators.
 
 %.lp "Special command keys"
 \item[\tb{Special command keys}]