Index: src/wp-admin/css/customize-nav-menus.css
===================================================================
--- src/wp-admin/css/customize-nav-menus.css	(revision 38210)
+++ src/wp-admin/css/customize-nav-menus.css	(working copy)
@@ -474,6 +474,11 @@
 	background: #fff;
 	-webkit-transition: background-color 0.15s;
 	transition: background-color 0.15s;
+	/* Reset the value inherited from the base .accordion-section-title style. Ticket #37589. */
+	-webkit-user-select: auto;
+	-moz-user-select: auto;
+	-ms-user-select: auto;
+	user-select: auto;
 }
 
 #available-menu-items .open .accordion-section-title,