diff -r 000000000000 -r 6474c204b198 browser/themes/windows/devtools/debugger.css
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/themes/windows/devtools/debugger.css	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,17 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+%include ../../shared/devtools/debugger.inc.css
+
+.devtools-sidebar-tabs > tabs > tab {
+  min-height: 22px !important;
+}
+
+#instruments-pane-toggle:hover {
+  -moz-image-region: rect(0px,32px,16px,16px);
+}
+
+#instruments-pane-toggle:hover:active {
+  -moz-image-region: rect(0px,48px,16px,32px);
+}