/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		checkLayer()
Description:	event handler to turn a hidden layer on/off according to
				it's sister
Arguments:		map object
Return:			none
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
function checkLayer(){
	var myMap = getMap();
	myMap.setAutoRefresh(false);
	var myLayerVis=myMap.getMapLayer('Zoning').isVisible();
	var myLayerVis2=myMap.getMapLayer('Landuse').isVisible();
	if (myLayerVis || myLayerVis2){
		myMap.getMapLayer('CorpLimits').setVisibility(false);
	}else{
		myMap.getMapLayer('CorpLimits').setVisibility(true);
	}
	myMap.setAutoRefresh(true);
}