Bootstrap 3 collapsing arrow indicators.

themes/bootstrap3/css/bootstrap-custom.css

@@ -129,13 +129,20 @@ label.list-group-item {
   }
 }
 
-.sidebar .title.collapsed {
+.sidebar .title {
   cursor: pointer;
 }
+.sidebar .title:before {
+  content:'\25B2';
+  float:right;
+}
 
-.sidebar .title.collapsed.collapsed {
+.sidebar .title.collapsed {
   border-radius: 4px;
 }
+.sidebar .title.collapsed:before {
+  content:'\25BC';
+}
 
 .sidebar .collapse .list-group-item,.sidebar .collapsing .list-group-item {
   border-top-left-radius: 0px;

themes/bootstrap3/less/bootstrap.less

@@ -161,6 +161,13 @@ label.list-group-item {border-radius:0;font-weight:normal;margin-top:0;padding-l
     cursor:pointer;
     &.collapsed {
       border-radius:@border-radius-base;
+      &:after {
+        content:'\25BC';
+      }
+    }
+    &:after {
+      content:'\25B2';
+      float:right;
     }
   }
   .collapse,.collapsing {