[plt-scheme] How is caps lock supposed to be handled in keymaps?

From: Danny Yoo (dyoo at hkn.eecs.berkeley.edu)
Date: Mon Jan 22 22:28:34 EST 2007

Hi everyone,

I'm attacking a very nasty bug in DivaScheme involving caps lock.  Given a 
keymap%, I bind my own custom functions by using ADD-FUNCTION.  However, 
it appears that when Caps Lock is on, the associated keys aren't found.

I've been able to work around the issue by intercepting key-event%s that 
look like they've been affected by caps lock, and transforming them so 
that they don't:

   ;; A grab-key-function that looks at unmapped keys that look like
   ;; capslock is on, and tries to remap to keys that aren't caps-locked.
   (define (ignores-caps-lock-grab-key-function str km editor event)
     (define (caps-lock-on?)
       (and (not str)
            (is-a? event key-event%)
            (char? (send event get-key-code))
            (char-upper-case? (send event get-key-code))
            (not (send event get-shift-down))))
     (define (copy-key/downcase)
       (let ([key-event
              (new key-event%
                   [key-code (char-downcase (send event get-key-code))]
                   [shift-down #f]
                   [control-down (send event get-control-down)]
                   [meta-down (send event get-meta-down)]
                   [alt-down (send event get-alt-down)]
                   [x (send event get-x)]
                   [y (send event get-y)]
                   [time-stamp (send event get-time-stamp)])])
         (send key-event set-other-altgr-key-code
               (send key-event get-other-altgr-key-code))
         (send key-event set-other-shift-altgr-key-code
               (send key-event get-other-shift-altgr-key-code))
         (send key-event set-other-shift-key-code
               (send key-event get-other-shift-key-code))
     (if (caps-lock-on?)
         (send km handle-key-event editor

   ;; later on in the code:
    (send command-keymap set-grab-key-function

I've been reading the documentation in MrEd, but there's nothing in there 
about Caps Lock, so I have no idea if what I'm doing here is actually 
correct.  *grin*

Is what I'm doing the right thing to do, and if so, can the situation 
involving Caps Lock be better documented in the MrEd docs?  Thanks!

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