Bug #23365 --> view headers all as a popup menu define the popup (just an empty box).

We'll dynamically generate the contents of this box.

mailnews/base/resources/content/messenger.xul

@@ -287,12 +287,18 @@ Rights Reserved.
 			  accesskey=""
 			  oncommand="MsgFolderProperties();"/>
 	</popup>
-  <popup id="emailAddressPopup"  oncreate="return fillEmailAddressMenu(document.popupNode);" popupanchor="bottomleft">
+	<popup id="emailAddressPopup"  oncreate="return fillEmailAddressMenu(document.popupNode);" popupanchor="bottomleft">
       <menuitem value="&AddToAddressBook.label;"
                 oncommand="AddNodeToAddressBook(document.popupNode)"/>
       <menuitem value="&SendMailTo.label;"
                 oncommand="SendMailToNode(document.popupNode)"/>
 	</popup>
+
+	<popup id="allHeadersPopup"  oncreate="return fillAllHeadersPopup(document.popupNode);" popupanchor="bottomleft">
+		<box id="allHeadersPopupContainer">
+		</box>
+	</popup>
+
 	<popup id="messagePaneContext"/>
 </popupset>