diff --git a/xpfe/global/resources/skin/xul.css b/xpfe/global/resources/skin/xul.css
index f8a5a8beb9cc..3a39c834a9ef 100644
--- a/xpfe/global/resources/skin/xul.css
+++ b/xpfe/global/resources/skin/xul.css
@@ -14,7 +14,7 @@
 }
 
 *[collapsed="true"] {
-  visibility: collapsed;
+  visibility: collapse;
 }
 
 *[hidden="true"] {
diff --git a/xpfe/global/resources/skin/xulBindings.xml b/xpfe/global/resources/skin/xulBindings.xml
index f8304f0d8161..9480ead9f12e 100644
--- a/xpfe/global/resources/skin/xulBindings.xml
+++ b/xpfe/global/resources/skin/xulBindings.xml
@@ -428,7 +428,7 @@
 
   <binding id="popups">
     <content>
-      <xul:box class="internal-box" orient="vertical">
+      <xul:box class="internal-box" orient="vertical" flex="1" style="overflow: auto">
         <children/>
       </xul:box>
     </content>