function _fit(target, parent, fit){
			if (!parent.length){return false;}
			var t = $(target)[0];
			var p = parent[0];
			var fcount = p.fcount || 0;
			if (fit){
				if (!t.fitted){
					t.fitted = true;
					p.fcount = fcount + 1;
					$(p).addClass('panel-noscroll');
					if (p.tagName == 'BODY'){
						$('html').addClass('panel-fit');
					}
				}
				return {
					width: ($(p).width()||1),
					height: ($(p).height()||1)
				};
			} else {
				if (t.fitted){
					t.fitted = false;
					p.fcount = fcount - 1;
					if (p.fcount == 0){
						$(p).removeClass('panel-noscroll');
						if (p.tagName == 'BODY'){
							$('html').removeClass('panel-fit');
						}
					}
				}
				return false;
			}
		}
extend plugin to set box model height