Waits until {condition} evaluates to |TRUE|, where {condition} is a |Funcref| or |string| containing an expression. {timeout} is the maximum waiting time in milliseconds, -1 means forever. Condition is evaluated on user events, internal events, and every {interval} milliseconds (default: 200). Returns a status integer: 0 if the condition was satisfied before timeout -1 if the timeout was exceeded -2 if the function was interrupted (by |CTRL-C|) -3 if an error occurred