// addKeyString adds a new key binding string to XUtil.Keystrings.
// The invariant is that each key string appears once and only once.
func addKeyString(xu *xgbutil.XUtil, callback xgbutil.CallbackKey,
evtype int, win xproto.Window, keyStr string, grab bool) {
xu.KeybindsLck.Lock()
defer xu.KeybindsLck.Unlock()
k := xgbutil.KeyString{
Str: keyStr,
Callback: callback,
Evtype: evtype,
Win: win,
Grab: grab,
}
xu.Keystrings = append(xu.Keystrings, k)
}