NAME
        SetEditHook -- Set global processing for string gadgets. (V36)

    SYNOPSIS
        OldHook = SetEditHook( hook )
        D0                     A0

        struct hook *setedithook( struct hook * );

    FUNCTION
        Sets new global editing hook for string gadgets.

        WARNING: The use and integration of this function has not
        been explored, and thus should be considered a risky function.
        Do *NOT* use this in a commercial product until further notice.

    INPUTS
        hook -- a pointer to a struct hook which determines a function
          in your code to be called every time the user types a key.
          This is done before control is passed to the gadget custom
          editing hook, so affects ALL string gadgets.

    RESULT
        Returns previous global edit hook structure.  You may need this
        hook if you wish to invoke the previous edit hook's behavior
        in addition to your own.

    NOTES
        There are a few key differences between a global edit hook and the
        more famililar per-gadget StringExtend->EditHook field.  In the
        case of the latter, the hook's creator supplies a WorkBuffer.
        Intuition's idea of the result of a keystroke is stored in
        the sgwork structure (which references the workbuffer).  the
        state of the gadget before Intuition's hook acted is available in
        the StringInfo->Buffer, ->BufferPos, and ->NumChars fields.

        In the case of a global editing hook, your hook _becomes_
        Intuition's hook, which affects all gadgets, most of which
        do not have a WorkBuffer.  This means that if you invoke
        Intuition's original hook (which you got as the result of this
        function), there isn't any easy way for you to "undo" that after
        the fact.  This means that if Intuition's behavior for certain
        keystrokes is incompatible with your hook's objectives, then
        you must avoid calling Intuition's hook for those keys.  One
        approach is to run through your hook's code first, acting on
        those keys you wish to recognize.  Then, call Intuition's
        hook for those keys you do not recognize, or for those keys
        whose default actions you wish to add to.

        Do not forget to set SGA_REDISPLAY when needed (see sghooks.h),
        and please be sure to give the SGWork->EditOp field a value
        which is as meaningful as possible.

        Currently, only SGH_KEY messages are sent to the global edit
        hook, though custom edit hooks do receive SGH_CLICK messages
        in addition.

        Finally, there is currently no arbitration between a global
        edit hook and a custom edit hook as to ownership of keystrokes.
        It would be fair to expect that a custom edit hook would be
        written to match the current Intuition edit hook.  If your
        global edit hook acts on (say) up and down arrow keystrokes,
        an undesirable result may occur if some string gadget's custom
        hook also acts on these keystrokes.  There is currently
        no easy way to resolve this issue.

    BUGS

    SEE ALSO