forbid text selection on normal headline rows / unexpanded CDM rows to prevent annoying glitches when selecting ranges etc

css/cdm.less

@@ -367,6 +367,10 @@ div#floatingTitle.Unread a.title {
 
 }
 
+.cdm.expandable:not(.active) {
+	user-select : none;
+}
+
 .cdm.expandable.Unread {
 	background : white;
 }