I think we can add the Han/En as a global hotkey for f11.

Hopefully we do more for f12.

Warren, can you find out the keysym?

Though that would just duplicate the Hangul key hotkey?

Adding "Alt_R" to the list of ibus global hotkeys makes this work, although you need to restart ibus for it to take effect.

Hangul button, KO layout, KO keyboard:
    state 0x10, keycode 130 (keysym 0xff31, Hangul), same_screen YES,
Alt_R button,  KO layout, KO keyboard:
    state 0x18, keycode 108 (keysym 0xffea, Alt_R), same_screen YES,
Alt_R button, US layout,  US keyboard:
    state 0x10, keycode 108 (keysym 0xffea, Alt_R), same_screen YES,
Alt_R button, JP layout,  JP keyboard:
    state 0x10, keycode 108 (keysym 0xffea, Alt_R), same_screen YES,

Just do it.  Not ideal, but it will work.

Using Alt_R press key event as trigger will conflict some menu keyboard shortcut. Like: Alt-F for file menu. We can only use Alt_R release key event (Release + Alt_R)as the trigger. But it still has a problem.
Please consider the below case.
When user press Alt+F, ibus will receive events like Alt_R press, F press, F release, Alt release.  In this case, we should consider the last Alt release event as trigger hotkey. IBus use below logic to check this case.

if (modifier & ReleaseMask) and (keyval == previous_keyval == Key_XX) then
    do trigger
else
    ignore

This logic works for most keys with release modifier except the Alt. When alt is pressed, the follow key events will not be sent to ibus. (For Alt+F, ibus only get two event, Alt_R press and Alt_R release, The F key event s are stolen ). I guess the gtk filters key events with Alt modifier. So ibus can not handle it correctly.

The bug where Alt + Release isn't detected is filed separately in Bug #495431.

I am moving this to F11Target since the En mode won't land in time for F11 freeze.

Fixed in ibus-1_1_0_20090413-3_fc11