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A broadcaster is used when you want multiple elements to share one or more attribute values, or when you want elements to respond to a state change. Any elements that are observing the broadcaster will share the attributes placed on the broadcaster. For instance, if the broadcaster has a label attribute, the observers will use that label. If the label changes, the labels of the observers will update automatically. An onbroadcast event will be sent to the observers when a change is made.
For menuitems or buttons that just want to have their disabled status set when the feature should be disabled, you should use a command element instead.