The dispatching modes describe how the widgets library sends out messages. Currently there are three modes:
|xpMode_Direct||"0"||The message will only be sent to the target widget.|
The message is sent to the target widget, then up the chain of parents until the message is
handled or a parentless widget is reached.
|xpMode_Recursive||"2"||The message is sent to the target widget and then all of its children recursively depth-first.|
|xpMode_DirectAllCallbacks||"3"||The message is snet just to the target, but goes to every callback, even if it is handled.|
|xpMode_Once||"4"||The message is only sent to the very first handler even if it is not accepted. (This is really only useful for some internal widget library functions.)|