function checkOverflow(){
	var oMainCont=document.getElementById('mainCont');
	var oHeaderCont=document.getElementById('headerCont');
	
	var oMainContHeight=oMainCont.scrollHeight;
	var oHeaderContHeight=oHeaderCont.scrollHeight+12;

	switch(browserComp) {
		case 'IE': {
			var oWindowHeight=document.body.offsetHeight;
			break;
		}
		case 'NS': {
			var oWindowHeight=window.innerHeight;
			break;
		}
		case 'OP': {
			var oWindowHeight=window.innerHeight;
			break;
		}
	}
	var oMainContDispHeight=oWindowHeight-oHeaderContHeight;
	if(oMainContHeight > oMainContDispHeight){
		oMainCont.style.height=oMainContDispHeight;
		oMainCont.style.overflowY="auto";
	}
	else if(oMainContHeight <= oMainContDispHeight){
		oMainCont.style.height=oMainContDispHeight;
		oMainCont.style.overflow="hidden";
	}
}