Position: Check for fraction support.

Author: scottgonzalez

ui/jquery.ui.position.js

@@ -183,6 +183,12 @@ $.fn.position = function( options ) {
 		position.left += myOffset[ 0 ];
 		position.top += myOffset[ 1 ];
 
+		// if the browser doesn't support fractions, then round for consistent results
+		if ( !$.support.offsetFractions ) {
+			position.left = Math.round( position.left );
+			position.top = Math.round( position.top );
+		}
+
 		collisionPosition = {
 			marginLeft: marginLeft,
 			marginTop: marginTop
@@ -406,6 +412,45 @@ $.ui.position = {
 	}
 };
 
+// fraction support test
+(function () {
+	var testElement, testElementParent, testElementStyle, offsetLeft, i
+		body = document.getElementsByTagName( "body" )[ 0 ], 
+		div = document.createElement( "div" );
+
+	//Create a "fake body" for testing based on method used in jQuery.support
+	testElement = document.createElement( body ? "div" : "body" );
+	testElementStyle = {
+		visibility: "hidden",
+		width: 0,
+		height: 0,
+		border: 0,
+		margin: 0,
+		background: "none"
+	};
+	if ( body ) {
+		jQuery.extend( testElementStyle, {
+			position: "absolute",
+			left: "-1000px",
+			top: "-1000px"
+		});
+	}
+	for ( i in testElementStyle ) {
+		testElement.style[ i ] = testElementStyle[ i ];
+	}
+	testElement.appendChild( div );
+	testElementParent = body || document.documentElement;
+	testElementParent.insertBefore( testElement, testElementParent.firstChild );
+
+	div.style.cssText = "position: absolute; left: 10.7432222px;";
+
+	offsetLeft = $( div ).offset().left;
+	$.support.offsetFractions = offsetLeft > 10 && offsetLeft < 11;
+
+	testElement.innerHTML = "";
+	testElementParent.removeChild( testElement );
+})();
+
 // DEPRECATED
 if ( $.uiBackCompat !== false ) {
 	// offset option