The highlighter now uses a <pre> instead of a <textarea>. Much better!

web/less/codemirror.less

@@ -1,10 +1,16 @@
 .CodeMirror {
   line-height: 1em;
   font-family: Monaco,"Courier New","DejaVu Sans Mono","Bitstream Vera Sans Mono",monospace;
+
+  /* Necessary so the scrollbar can be absolutely positioned within the wrapper on Lion. */
+  position: relative;
+  /* This prevents unwanted scrollbars from showing up on the body and wrapper in IE. */
+  overflow: hidden;
 }
 
 .CodeMirror-scroll {
-  overflow: auto;
+  overflow-x: auto;
+  overflow-y: hidden;
   height: 500px;
   /* This is needed to prevent an IE[67] bug where the scrolled content
      is visible outside of the scrolling box. */
@@ -12,6 +18,37 @@
   outline: none;
 }
 
+/* Vertical scrollbar */
+.CodeMirror-scrollbar {
+  float: right;
+  overflow-x: hidden;
+  overflow-y: scroll;
+
+  /* This corrects for the 1px gap introduced to the left of the scrollbar
+     by the rule for .CodeMirror-scrollbar-inner. */
+  margin-left: -1px;
+}
+.CodeMirror-scrollbar-inner {
+  /* This needs to have a nonzero width in order for the scrollbar to appear
+     in Firefox and IE9. */
+  width: 1px;
+}
+.CodeMirror-scrollbar.cm-sb-overlap {
+  /* Ensure that the scrollbar appears in Lion, and that it overlaps the content
+     rather than sitting to the right of it. */
+  position: absolute;
+  z-index: 1;
+  float: none;
+  right: 0;
+  min-width: 12px;
+}
+.CodeMirror-scrollbar.cm-sb-nonoverlap {
+  min-width: 12px;
+}
+.CodeMirror-scrollbar.cm-sb-ie7 {
+  min-width: 18px;
+}
+
 .CodeMirror-gutter {
   position: absolute; left: 0; top: 0;
   z-index: 10;
@@ -29,6 +66,11 @@
 .CodeMirror-lines {
   padding: .4em;
   white-space: pre;
+  cursor: text;
+}
+.CodeMirror-lines * {
+  /* Necessary for throw-scrolling to decelerate properly on Safari. */
+  pointer-events: none;
 }
 
 .CodeMirror pre {
@@ -122,4 +164,4 @@ span.cm-emstrong {font-style: italic; font-weight: bold;}
 span.cm-link {text-decoration: underline;}
 
 div.CodeMirror span.CodeMirror-matchingbracket {color: #0f0;}
-div.CodeMirror span.CodeMirror-nonmatchingbracket {color: #f22;}
+div.CodeMirror span.CodeMirror-nonmatchingbracket {color: #f22;}