IE6 will shrink-wrap elements with layout instead of allowing content to flow outside of the border-box. Add a test for this and do not remove the overflow property after an animation in IE6.

src/effects.js

@@ -36,17 +36,23 @@ jQuery.fn.extend({
 			return this.animate( genFx("show", 3), speed, easing, callback);
 		} else {
 			for ( var i = 0, j = this.length; i < j; i++ ) {
+				// Reset the inline display of this element to learn if it is
+				// being hidden by cascaded rules or not
+				if ( !jQuery.data(this[i], "olddisplay") && this[i].style.display === "none" ) {
+					this[i].style.display = "";
+				}
+
 				// Set elements which have been overridden with display: none
 				// in a stylesheet to whatever the default browser style is
 				// for such an element
-				if ( jQuery.css( this[i], "display" ) === "none" && this[i].style.display !== "none" ) {
+				if ( jQuery.css( this[i], "display" ) === "none" && this[i].style.display === "" ) {
 					jQuery.data(this[i], "olddisplay", defaultDisplay(this[i].nodeName));
 				}
 			}
 
-			// Set the display of the elements in a second loop
+			// Set the display of most of the elements in a second loop
 			// to avoid the constant reflow
-			for ( i = 0, j = this.length; i < j; i++ ) {
+			for ( i = 0; i < j; i++ ) {
 				this[i].style.display = jQuery.data(this[i], "olddisplay") || "";
 			}
 
@@ -59,17 +65,17 @@ jQuery.fn.extend({
 			return this.animate( genFx("hide", 3), speed, easing, callback);
 
 		} else {
-			for ( var i = 0, l = this.length; i < l; i++ ) {
+			for ( var i = 0, j = this.length; i < j; i++ ) {
 				var old = jQuery.data(this[i], "olddisplay");
-				if ( !old && old !== "none" ) {
+				if ( !old ) {
 					jQuery.data( this[i], "olddisplay", jQuery.css( this[i], "display" ) );
 				}
 			}
 
 			// Set the display of the elements in a second loop
 			// to avoid the constant reflow
-			for ( var j = 0, k = this.length; j < k; j++ ) {
+			for ( i = 0; i < j; i++ ) {
-				this[j].style.display = "none";
+				this[i].style.display = "none";
 			}
 
 			return this;
@@ -115,7 +121,8 @@ jQuery.fn.extend({
 			// test suite
 
 			var opt = jQuery.extend({}, optall), p,
-				hidden = this.nodeType === 1 && jQuery(this).is(":hidden"),
+				isElement = this.nodeType === 1,
+				hidden = isElement && jQuery(this).is(":hidden"),
 				self = this;
 
 			for ( p in prop ) {
@@ -131,7 +138,7 @@ jQuery.fn.extend({
 					return opt.complete.call(this);
 				}
 
-				if ( ( p === "height" || p === "width" ) ) {
+				if ( isElement && ( p === "height" || p === "width" ) ) {
 					// Make sure that nothing sneaks out
 					// Record all 3 overflow attributes because IE does not
 					// change the overflow attribute when overflowX and
@@ -141,8 +148,8 @@ jQuery.fn.extend({
 					// Set display property to inline-block for height/width
 					// animations on inline elements that are having width/height
 					// animated
-					if ( jQuery.curCSS( this, "display" ) === "inline" &&
+					if ( jQuery.css( this, "display" ) === "inline" &&
-					jQuery.curCSS( this, "float" ) === "none" ) {
+						jQuery.css( this, "float" ) === "none" ) {
 						if ( !jQuery.support.inlineBlockNeedsLayout ) {
 							this.style.display = "inline-block";
 						} else {
@@ -168,7 +175,7 @@ jQuery.fn.extend({
 				}
 			}
 
-			if ( opt.overflow != null ) {
+			if ( opt.overflow != null || (jQuery.support.shrinkWrapBlocks && isElement) ) {
 				this.style.overflow = "hidden";
 			}
 
@@ -401,7 +408,7 @@ jQuery.fx.prototype = {
 
 			if ( done ) {
 				// Reset the overflow
-				if ( this.options.overflow != null ) {
+				if ( this.options.overflow != null && (!jQuery.support.shrinkWrapBlocks || !jQuery.css( this.elem, "hasLayout" )) ) {
 					this.elem.style.overflow = this.options.overflow[0];
 					this.elem.style.overflowX = this.options.overflow[1];
 					this.elem.style.overflowY = this.options.overflow[2];

src/support.js

@@ -67,6 +67,7 @@
 		noCloneEvent: true,
 		boxModel: null,
 		inlineBlockNeedsLayout: false,
+		shrinkWrapBlocks: false,
 		reliableHiddenOffsets: true
 	};
 
@@ -120,17 +121,25 @@
 		document.body.appendChild( div );
 		jQuery.boxModel = jQuery.support.boxModel = div.offsetWidth === 2;
 
-		// Check if natively block-level elements act like inline-block
-		// elements when setting their display to 'inline'
-		// (IE < 8 does this)
 		if ( 'zoom' in div.style ) {
+			// Check if natively block-level elements act like inline-block
+			// elements when setting their display to 'inline' and giving
+			// them layout
+			// (IE < 8 does this)
 			div.style.display = 'inline';
-
-			// Layout is necessary to trigger this “feature”
 			div.style.zoom = 1;
 			jQuery.support.inlineBlockNeedsLayout = div.offsetWidth === 2;
+
+			// Check if elements with layout shrink-wrap their children
+			// (IE 6 does this)
+			div.style.display = '';
+			div.innerHTML = '<div style="width:4px;"></div>';
+			jQuery.support.shrinkWrapBlocks = div.offsetWidth !== 2;
 		}
 
+		div.innerHTML = '<table><tr><td style="padding:0;display:none"></td><td>t</td></tr></table>';
+		var tds = div.getElementsByTagName('td');
+
 		// Check if table cells still have offsetWidth/Height when they are set
 		// to display:none and there are still other visible table cells in a
 		// table row; if so, offsetWidth/Height are not reliable for use when
@@ -138,12 +147,18 @@
 		// display:none (it is still safe to use offsets if a parent element is
 		// hidden; don safety goggles and see bug #4512 for more information).
 		// (only IE 8 fails this test)
-		div.innerHTML = '<table><tr><td style="display:none"></td><td>t</td></tr></table>';
+		jQuery.support.reliableHiddenOffsets = tds[0].offsetHeight === 0;
-		jQuery.support.reliableHiddenOffsets = div.getElementsByTagName('td')[0].offsetHeight === 0;
+
+		tds[0].style.display = '';
+		tds[1].style.display = 'none';
+
+		// Check if empty table cells still have offsetWidth/Height
+		// (IE < 8 fail this test)
+		jQuery.support.reliableHiddenOffsets = jQuery.support.reliableHiddenOffsets && tds[0].offsetHeight === 0;
 		div.innerHTML = '';
 
 		document.body.removeChild( div ).style.display = 'none';
-		div = null;
+		div = tds = null;
 	});
 
 	// Technique from Juriy Zaytsev

test/unit/effects.js

@@ -37,6 +37,7 @@ test("show()", function() {
 		ok( pass, "Show with " + name + " does not call animate callback" );
 	});
 
+	// #show-tests * is set display: none in CSS
 	jQuery("#main").append('<div id="show-tests"><div><p><a href="#"></a></p><code></code><pre></pre><span></span></div><table><thead><tr><th></th></tr></thead><tbody><tr><td></td></tr></tbody></table><ul><li></li></ul></div>');
 
 	var old = jQuery("#show-tests table").show().css("display") !== "table";
@@ -69,6 +70,7 @@ test("show(Number) - other displays", function() {
 	QUnit.reset();
 	stop();
 
+	// #show-tests * is set display: none in CSS
 	jQuery("#main").append('<div id="show-tests"><div><p><a href="#"></a></p><code></code><pre></pre><span></span></div><table><thead><tr><th></th></tr></thead><tbody><tr><td></td></tr></tbody></table><ul><li></li></ul></div>');
 
 	var old = jQuery("#show-tests table").show().css("display") !== "table",
@@ -124,7 +126,7 @@ test("animate negative height", function() {
 	});
 });
 
-test("animate inline width/height", function() {
+test("animate block as inline width/height", function() {
 	expect(3);
 	stop();
 	jQuery("#foo").css({ display: "inline", width: '', height: '' }).animate({ width: 42, height: 42 }, 100, function() {
@@ -135,6 +137,20 @@ test("animate inline width/height", function() {
 	});
 });
 
+test("animate native inline width/height", function() {
+	expect(3);
+	stop();
+	jQuery("#foo").css({ display: "", width: '', height: '' })
+		.append('<span>text</span>')
+		.children('span')
+			.animate({ width: 42, height: 42 }, 100, function() {
+				equals( jQuery(this).css("display"), "inline-block", "inline-block was set on non-floated inline element when animating width/height" );
+				equals( this.offsetWidth, 42, "width was animated" );
+				equals( this.offsetHeight, 42, "height was animated" );
+				start();
+			});
+});
+
 test("animate block width/height", function() {
 	expect(3);
 	stop();
@@ -158,12 +174,31 @@ test("animate table width/height", function() {
 	});
 });
 
+test("animate table-row width/height", function() {
+	expect(3);
+	stop();
+	var tr = jQuery("#table")
+		.attr({ "cellspacing": 0, "cellpadding": 0, "border": 0 })
+		.html("<tr style='height:42px;'><td style='padding:0;'><div style='width:20px;height:20px;'></div></td></tr>")
+		.find("tr");
+
+	// IE<8 uses “block” instead of the correct display type
+	var displayMode = tr.css("display") !== "table-row" ? "block" : "table-row";
+
+	tr.animate({ width: 10, height: 10 }, 100, function() {
+		equals( jQuery(this).css("display"), displayMode, "display mode is correct" );
+		equals( this.offsetWidth, 20, "width animated to shrink wrap point" );
+		equals( this.offsetHeight, 20, "height animated to shrink wrap point" );
+		start();
+	});
+});
+
 test("animate table-cell width/height", function() {
 	expect(3);
 	stop();
 	var td = jQuery("#table")
 		.attr({ "cellspacing": 0, "cellpadding": 0, "border": 0 })
-		.append("<tr><td style='width:42px;height:42px;padding:0;'><div style='width:20px;height:20px;'></div></td></tr>")
+		.html("<tr><td style='width:42px;height:42px;padding:0;'><div style='width:20px;height:20px;'></div></td></tr>")
 		.find("td");
 
 	// IE<8 uses “block” instead of the correct display type
@@ -425,9 +460,10 @@ test("toggle()", function() {
 });
 
 jQuery.checkOverflowDisplay = function(){
-	var o = jQuery.css( this, "overflow" );
+	var o = jQuery.css( this, "overflow" ),
+		expected = jQuery.support.shrinkWrapBlocks ? "hidden" : "visible";
 
-	equals(o, "visible", "Overflow should be visible: " + o);
+	equals(o, expected, "Overflow should be " + expected + ": " + o);
 	equals(jQuery.css( this, "display" ), "inline", "Display shouldn't be tampered with.");
 
 	start();
@@ -617,6 +653,9 @@ jQuery.checkState = function(){
 	var self = this;
 	jQuery.each(this.save, function(c,v){
 		var cur = self.style[ c ] || jQuery.css(self, c);
+		if ( c === "overflow" && jQuery.support.shrinkWrapBlocks ) {
+			v = "hidden";
+		}
 		equals( cur, v, "Make sure that " + c + " is reset (Old: " + v + " Cur: " + cur + ")");
 	});
 	start();