Index: tests/admin/includesScreen.php
===================================================================
--- tests/admin/includesScreen.php	(revision 1035)
+++ tests/admin/includesScreen.php	(working copy)
@@ -32,6 +32,33 @@
 		'options-writing.php' => array( 'base' => 'options-writing', 'id' => 'options-writing' ),
 	);
 
+	var $core_screens_guid = array(
+		'site:dashboard' => array( 'base' => 'dashboard', 'id' => 'dashboard' ),
+		'site:edit:post' => array( 'base' => 'edit', 'id' => 'edit-post', 'post_type' => 'post' ),
+		'site:post:post'=> array( 'action' => 'add', 'base' => 'post', 'id' => 'post', 'post_type' => 'post' ),
+		'site:edit-tags:post_tag:post' => array( 'base' => 'edit-tags', 'id' => 'edit-post_tag', 'post_type' => 'post', 'taxonomy' => 'post_tag' ),
+		'site:edit-tags:category:post' => array( 'base' => 'edit-tags', 'id' => 'edit-category', 'post_type' => 'post', 'taxonomy' => 'category' ),
+		'site:upload' => array( 'base' => 'upload', 'id' => 'upload' ),
+		'site:media' => array( 'action' => 'add', 'base' => 'media', 'id' => 'media' ),
+		'site:edit:page' => array( 'base' => 'edit', 'id' => 'edit-page', 'post_type' => 'page' ),
+		'site:link-manager' => array( 'base' => 'link-manager', 'id' => 'link-manager' ),
+		'site:link' => array( 'action' => 'add', 'base' => 'link', 'id' => 'link' ),
+		'site:edit-tags:link_category:link' => array( 'base' => 'edit-tags', 'id' => 'edit-link_category', 'taxonomy' => 'link_category' ),
+		'site:edit-comments' => array( 'base' => 'edit-comments', 'id' => 'edit-comments' ),
+		'site:themes' => array( 'base' => 'themes', 'id' => 'themes' ),
+		'site:widgets' => array( 'base' => 'widgets', 'id' => 'widgets' ),
+		'site:nav-menus' => array( 'base' => 'nav-menus', 'id' => 'nav-menus' ),
+		'site:plugins' => array( 'base' => 'plugins', 'id' => 'plugins' ),
+		'site:users' => array( 'base' => 'users', 'id' => 'users' ),
+		'site:user' => array( 'action' => 'add', 'base' => 'user', 'id' => 'user' ),
+		'site:profile' => array( 'base' => 'profile', 'id' => 'profile' ),
+		'site:tools' => array( 'base' => 'tools', 'id' => 'tools' ),
+		'site:import' => array( 'base' => 'import', 'id' => 'import' ),
+		'site:export' => array( 'base' => 'export', 'id' => 'export' ),
+		'site:options-general' => array( 'base' => 'options-general', 'id' => 'options-general' ),
+		'site:options-writing' => array( 'base' => 'options-writing', 'id' => 'options-writing' ),	
+	);
+
 	function setUp() {
 		set_current_screen( 'front' );
 	}
@@ -91,6 +118,34 @@
 		}
 	}
 
+	function test_set_current_screen_with_guid() {
+		global $current_screen;
+
+		foreach ( $this->core_screens_guid as $guid => $screen ) {
+			$screen = (object) $screen;
+			set_current_screen( $guid );
+			$this->assertEquals( $screen->id, $current_screen->id, $guid );
+			$this->assertEquals( $screen->base, $current_screen->base, $guid );
+			if ( isset( $screen->action ) )
+				$this->assertEquals( $screen->action, $current_screen->action, $guid );
+			if ( isset( $screen->post_type ) )
+				$this->assertEquals( $screen->post_type, $current_screen->post_type, $guid );
+			else
+				$this->assertEmpty( $current_screen->post_type, $guid );
+			if ( isset( $screen->taxonomy ) )
+				$this->assertEquals( $screen->taxonomy, $current_screen->taxonomy, $guid );
+
+			$this->assertTrue( $current_screen->in_admin() );
+			$this->assertTrue( $current_screen->in_admin( 'site' ) );
+			$this->assertFalse( $current_screen->in_admin( 'network' ) );
+			$this->assertFalse( $current_screen->in_admin( 'user' ) );
+			$this->assertFalse( $current_screen->in_admin( 'garbage' ) );
+			
+			// With convert_to_screen(), the same ID should return the exact $current_screen.
+			$this->assertSame( $current_screen, convert_to_screen( $screen->id ), $guid );
+		}
+	}
+
 	function test_post_type_as_hookname() {
 		$screen = convert_to_screen( 'page' );
 		$this->assertEquals( $screen->post_type, 'page' );