Button: Added user-select none

Author: jaspermdegroot

themes/base/button.css

@@ -18,6 +18,10 @@
 	vertical-align: middle;
 	text-align: center;
 	overflow: visible; /* removes extra width in IE */
+	-webkit-user-select: none;
+	-moz-user-select: none;
+	-ms-user-select: none;
+	user-select: none;
 }
 
 .ui-button,