Sets the picture to activated while a interface is active. Good for indicating trasmit status. By default it will be set in the appstart actions, so it will be used as a default for all pages. Otherwise you can set it for each page individually by setting it in the pagestartactions, or even change it as part of a button action. To avoid, that the picture will be shown right from the start, you should disable it in your widget definition.

<action name="" string="settransmitterpicture" picturename="Picture Transmit" />