Get the effective layout index for a key in a given keyboard state.
@returns The layout index for the key in the given keyboard state. If
the given keycode is invalid, or if the key is not included in any
layout at all, returns XKB_LAYOUT_INVALID.
@invariant If the returned layout is valid, the following always holds:
@code
xkb_state_key_get_layout(state, key) < xkb_keymap_num_layouts_for_key(keymap, key)
@endcode
Get the effective layout index for a key in a given keyboard state.
@returns The layout index for the key in the given keyboard state. If the given keycode is invalid, or if the key is not included in any layout at all, returns XKB_LAYOUT_INVALID.
@invariant If the returned layout is valid, the following always holds: @code xkb_state_key_get_layout(state, key) < xkb_keymap_num_layouts_for_key(keymap, key) @endcode
@memberof xkb_state