If you want your control to be toggleable - i.e. to activate the first time the associated button is clicked, and to deactivate the next time it is clicked - set the isToggleable property within the initializeControl() method:
initializeControl: function(options)
{
this.isToggleable = true;
}
Examples of toggleable controls are: mobileViewer.Geolocate, mobileViewer.ShowClickableMarkers, mobileViewer.Legend.