Index: src/wp-admin/js/editor-expand.js
===================================================================
--- src/wp-admin/js/editor-expand.js	(revision 29472)
+++ src/wp-admin/js/editor-expand.js	(working copy)
@@ -22,7 +22,10 @@
 		mceUnbind = function(){},
 		fixedTop = false,
 		fixedBottom = false,
-		scrollTimer;
+		scrollTimer,
+		pageYOffsetAtTop = 130,
+		textEditorClonePaddingTop = 37,
+		autoresizeMinHeight = $window.height() - 310;
 
 	$textEditorClone.insertAfter( $textEditor );
 
@@ -31,7 +34,7 @@
 		'font-size': $textEditor.css( 'font-size' ),
 		'line-height': $textEditor.css( 'line-height' ),
 		'padding': $textEditor.css( 'padding' ),
-		'padding-top': 37,
+		'padding-top': textEditorClonePaddingTop,
 		'white-space': 'pre-wrap',
 		'word-wrap': 'break-word'
 	} );
@@ -88,8 +91,8 @@
 
 		hiddenHeight = $textEditorClone.height();
 
-		if ( hiddenHeight < 300 ) {
-			hiddenHeight = 300;
+		if ( hiddenHeight < autoresizeMinHeight ) {
+			hiddenHeight = autoresizeMinHeight;
 		}
 
 		if ( hiddenHeight === textEditorHeight ) {
@@ -112,7 +115,7 @@
 		mceEditor = editor;
 
 		// Set the minimum height to the initial viewport height.
-		editor.settings.autoresize_min_height = 300;
+		editor.settings.autoresize_min_height = autoresizeMinHeight;
 
 		// Get the necessary UI elements.
 		$visualTop = $contentWrap.find( '.mce-toolbar-grp' );
@@ -218,7 +221,7 @@
 			adminBarHeight = windowWidth > 600 ? $adminBar.height() : 0,
 			resize = type !== 'scroll',
 			visual = ( mceEditor && ! mceEditor.isHidden() ),
-			buffer = 200,
+			buffer = autoresizeMinHeight + adminBarHeight,
 			$top, $editor,
 			toolsHeight, topPos, topHeight, editorPos, editorHeight, editorWidth, statusBarHeight;
 
@@ -236,6 +239,7 @@
 		editorPos = $editor.offset().top;
 		editorHeight = $editor.outerHeight();
 		editorWidth = $editor.outerWidth();
+		borderWidth = 1;
 		statusBarHeight = visual ? $statusBar.outerHeight() : 0;
 
 		// Maybe pin the top.
@@ -256,7 +260,7 @@
 			$tools.css( {
 				position: 'fixed',
 				top: adminBarHeight,
-				width: editorWidth + 2
+				width: editorWidth + ( borderWidth * 2 )
 			} );
 		// Maybe unpin the top.
 		} else if ( fixedTop || resize ) {
@@ -287,7 +291,7 @@
 
 				$tools.css( {
 					position: 'absolute',
-					top: editorHeight - buffer + 1, // border
+					top: editorHeight - buffer + borderWidth, // border
 					width: $contentWrap.width()
 				} );
 			}
@@ -295,18 +299,18 @@
 
 		// Maybe adjust the bottom bar.
 		if ( ( ! fixedBottom || resize ) &&
-				// + 1 for the border around the .wp-editor-container.
-				( windowPos + windowHeight ) <= ( editorPos + editorHeight + bottomHeight + statusBarHeight + 1 ) ) {
+				// +[n] for the border around the .wp-editor-container.
+				( windowPos + windowHeight ) <= ( editorPos + editorHeight + bottomHeight + statusBarHeight + borderWidth ) ) {
 			fixedBottom = true;
 
 			$bottom.css( {
 				position: 'fixed',
 				bottom: 0,
-				width: editorWidth + 2,
+				width: editorWidth + ( borderWidth * 2 ),
 				borderTop: '1px solid #dedede'
 			} );
 		} else if ( ( fixedBottom || resize ) &&
-				( windowPos + windowHeight ) > ( editorPos + editorHeight + bottomHeight + statusBarHeight - 1 ) ) {
+				( windowPos + windowHeight ) > ( editorPos + editorHeight + bottomHeight + statusBarHeight - borderWidth ) ) {
 			fixedBottom = false;
 
 			$bottom.css( {
@@ -354,7 +358,7 @@
 	function on() {
 		// Scroll to the top when triggering this from JS.
 		// Ensures toolbars are pinned properly.
-		if ( window.pageYOffset && window.pageYOffset > 130 ) {
+		if ( window.pageYOffset && window.pageYOffset > pageYOffsetAtTop ) {
 			window.scrollTo( window.pageXOffset, 0 );
 		}
 
@@ -397,7 +401,7 @@
 
 		// Scroll to the top when triggering this from JS.
 		// Ensures toolbars are reset properly.
-		if ( window.pageYOffset && window.pageYOffset > 130 ) {
+		if ( window.pageYOffset && window.pageYOffset > pageYOffsetAtTop ) {
 			window.scrollTo( window.pageXOffset, 0 );
 		}