-#button-newmessage[disabled="true"] {
- list-style-image: url("chrome://messenger/skin/addressbook/icons/newmsg-disabled.gif") !important;
+#button-newmessage:not([disabled="true"]):hover,
+#button-newmessage:not([disabled="true"]):hover:active {
+ -moz-image-region: rect(105px 75px 126px 50px);