The patch adds a new setxkbgroup function to be used inside keys[]. It allows idempotent keyboard layout switching from dwm itself.

Suppose you've configured keyboard layouts in X server like this:

setxkbmap -option 'grp:rctrl_toggle' -layout 'us,ru,epo,gr(bare)'

And then have defined a few key bindings in the keys[] array in dwm config.h like this:

	{ MODKEY,                       XK_u,      setxkbgroup,    {.ui = 0 } },
	{ MODKEY,                       XK_r,      setxkbgroup,    {.ui = 1 } },
	{ MODKEY,                       XK_e,      setxkbgroup,    {.ui = 2 } },
	{ MODKEY,                       XK_g,      setxkbgroup,    {.ui = 3 } },

Configured like this, MOD+r in dwm immediately activates Russian layout, MOD+g switches to Greek and MOD+u gets the US layout. You don't need to track how many times to press Right Ctrl (or whatever) key to use a desired layout.