Bug 628049 - Improve the hover styling of split menus in the Firefox menu [r=dao, a=blocking]

browser/themes/winstripe/browser/browser-aero.css

@@ -321,3 +321,67 @@
 #close-button:hover:active {
   -moz-image-region: rect(32px, 49px, 48px, 32px);
 }
+
+/* ::::: splitmenu highlight style that imitates Windows 7 start menu ::::: */
+@media all and (-moz-windows-default-theme) {
+  .splitmenu-menuitem,
+  .splitmenu-menu {
+    -moz-appearance: none;
+    padding-top: 2px;
+    padding-bottom: 2px;
+    border: 1px solid transparent;
+  }
+  .splitmenu-menuitem {
+    -moz-margin-end: 0;
+  }
+  .splitmenu-menu {
+    -moz-margin-start: -1px;
+  }
+  .splitmenu-menuitem:-moz-locale-dir(ltr),
+  .splitmenu-menu:-moz-locale-dir(rtl) {
+    border-top-left-radius: 3px;
+    border-bottom-left-radius: 3px;
+  }
+  .splitmenu-menu:-moz-locale-dir(ltr),
+  .splitmenu-menuitem:-moz-locale-dir(rtl) {
+    border-top-right-radius: 3px;
+    border-bottom-right-radius: 3px;
+  }
+
+  .splitmenu-menuitem > .menu-text {
+    -moz-margin-start: 1px !important;
+    -moz-margin-end: 3px !important;
+  }
+  .splitmenu-menu > .menu-right {
+    -moz-margin-end: -3px;
+  }
+
+  .splitmenu-menuitem[iconic],
+  .splitmenu-menu[iconic] {
+    padding-bottom: 1px;
+  }
+  .splitmenu-menuitem[iconic] > .menu-iconic-left {
+    margin-top: -3px;
+    margin-bottom: -2px;
+    -moz-margin-start: -1px;
+  }
+  .splitmenu-menuitem[iconic] > .menu-iconic-text {
+    -moz-margin-start: 2px !important;
+    -moz-margin-end: 3px !important;
+  }
+  .splitmenu-menu[iconic] > .menu-right {
+    margin-top: -1px;
+  }
+
+  .splitmenu-menuitem[_moz-menuactive],
+  .splitmenu-menu[_moz-menuactive] {
+    background-image: -moz-linear-gradient(#fafbfd, #ebf3fd);
+    border-color: #aeccf1;
+  }
+
+  .splitmenu-menuitem[disabled][_moz-menuactive],
+  .splitmenu-menu[disabled][_moz-menuactive] {
+    background-image: -moz-linear-gradient(#f8f9f9, #eaeaea);
+    border-color: #d8d7d7;
+  }
+}