Landing pull request 581. Updates original patch by Orkel. Fixes #10006.

More Details:
 - https://github.com/jquery/jquery/pull/581
 - http://bugs.jquery.com/ticket/10006

src/effects.js

@@ -38,7 +38,8 @@ jQuery.fn.extend({
 					// Set elements which have been overridden with display: none
 					// in a stylesheet to whatever the default browser style is
 					// for such an element
-					if ( display === "" && jQuery.css(elem, "display") === "none" ) {
+					if ( (display === "" && jQuery.css(elem, "display") === "none") ||
+							!jQuery.contains( elem.ownerDocument.documentElement, elem ) ) {
 						jQuery._data( elem, "olddisplay", defaultDisplay(elem.nodeName) );
 					}
 				}

test/unit/effects.js

@@ -167,7 +167,7 @@ test("Persist correct display value", function() {
 	});
 });
 
-test("show() resolves correct default display #8099", function() {
+test("show() resolves correct default display (#8099)", function() {
 	expect(7);
 	var tt8099 = jQuery("<tt/>").appendTo("body"),
 			dfn8099 = jQuery("<dfn/>", { html: "foo"}).appendTo("body");
@@ -185,7 +185,60 @@ test("show() resolves correct default display #8099", function() {
 
 	tt8099.remove();
 	dfn8099.remove();
+});
+
+test( "show() resolves correct default display, detached nodes (#10006)", function(){
+	// Tests originally contributed by Orkel in
+	// https://github.com/jquery/jquery/pull/458
+	expect( 11 );
+
+	var div, span;
+
+	div = jQuery("<div class='hidden'>");
+	div.show().appendTo("#qunit-fixture");
+	equal( div.css("display"), "block", "Make sure a detached, pre-hidden( through stylesheets ) div is visible." );
+
+	div = jQuery("<div style='display: none'>");
+	div.show().appendTo("#qunit-fixture");
+	equal( div.css("display"), "block", "Make sure a detached, pre-hidden( through inline style ) div is visible." );
+
+	span = jQuery("<span class='hidden'/>");
+	span.show().appendTo("#qunit-fixture");
+	equal( span.css("display"), "inline", "Make sure a detached, pre-hidden( through stylesheets ) span has default display." );
+
+	span = jQuery("<span style='display: inline'/>");
+	span.show().appendTo("#qunit-fixture");
+	equal( span.css("display"), "inline", "Make sure a detached, pre-hidden( through inline style ) span has default display." );
+
+	div = jQuery("<div><div class='hidden'></div></div>").children("div");
+	div.show().appendTo("#qunit-fixture");
+	equal( div.css("display"), "block", "Make sure a detached, pre-hidden( through stylesheets ) div inside another visible div is visible." );
+
+	div = jQuery("<div><div style='display: none'></div></div>").children("div");
+	div.show().appendTo("#qunit-fixture");
+	equal( div.css("display"), "block", "Make sure a detached, pre-hidden( through inline style ) div inside another visible div is visible." );
+
+	div = jQuery("div.hidden");
+	div.detach().show();
+	equal( div.css("display"), "block", "Make sure a detached( through detach() ), pre-hidden div is visible." );
+	div.remove();
+
+	span = jQuery("<span>");
+	span.appendTo("#qunit-fixture").detach().show().appendTo("#qunit-fixture" );
+	equal( span.css("display"), "inline", "Make sure a detached( through detach() ), pre-hidden span has default display." );
+	span.remove();
+
+	div = jQuery("<div>");
+	div.show().appendTo("#qunit-fixture");
+	ok( !!div.get( 0 ).style.display, "Make sure not hidden div has a inline style." );
+
+	div = jQuery( document.createElement("div") );
+	div.show().appendTo("#qunit-fixture");
+	equal( div.css("display"), "block", "Make sure a pre-created element has default display." );
 
+	div = jQuery("<div style='display: inline'/>");
+	div.show().appendTo("#qunit-fixture");
+	equal( div.css("display"), "inline", "Make sure that element has same display when it was created." );
 });