[maemo-developers] hildon im to X key proxy

[From: Austin Che]

    I've been trying to get something like the following to work:
    
    - I want to be able to press power, menu or something like that to
    bring up the on-screen keyboard
    - Then any keys I press should be sent as normal X key events
    (i.e. same as if I pressed them on a keyboard)
    - If I press a hardware key like the menu button, the next key
    pressed on the vkb is sent as a ctrl character instead
    
    Here's my current implementation:
    
    - I create a hidden window. I create a new hildon IM context and
    set the hidden window to be the client.
    - Keys pressed on the vkb are caught via the "commit" signal and
    converted to a unicode character.
    - I use gdk_unicode_to_keyval to convert it to a GDK keyval which
    I believe has a 1-to-1 mapping to X keysyms
    - XChangeKeyboardMapping is used to set an arbitrary unused
    keycode to map to the desired keysym
    - I then use XTest to generate a fake key of the given keycode
    
    It mostly works but there are some issues:

    - I cannot make a completely hidden window. The best I can do is a
    1x1 pixel window that shows up as a white dot in the top left
    corner. Making it zero size, moving it off screen, or trying to
    make it transparent don't seem to work.

    - I set the hidden window to not accept-focus. This is so that
    when I use XTestFakeKeyEvent, the key is sent to the current top
    application. However, this also means the hidden window cannot
    directly get the hardware key presses. I can get it in other ways
    such as directly from the device file, but it seems like there
    should be a better solution. If I give the hidden proxy window the
    focus, I can't figure out how to lose the focus before sending the
    fake key.
    
    - When using it with something like the X terminal which normally
    pops up the vkb itself, it works for a couple characters (not
    repeatable how many characters) and then my proxy stops receiving
    keyboard events. I believe it's because the app realizes it has
    the focus and it resets the client window for the vkb to be
    itself. This problem doesn't exist when I use it with something
    that doesn't normally pop up the vkb (e.g. running emacs over X
    remotely). If there was some way to determine when the client
    window for the vkb has changed, that would probably be good enough
    to reset it back to the proxy window.

    - Normally, when the vkb pops up, the window underneath is
    automatically resized. But when doing the above, the top window is
    not resized so it ends up that the keyboard covers the bottom of
    the window. How can I force the window underneath to resize?

    - Is there some way to tell when the vkb has been hidden by the
      user?
    
    Any hints appreciated.