Bug #350768 --> add a folder pane context menu to the folder location toolbar button. rs=me

mail/base/content/mailWindowOverlay.xul

@@ -1955,10 +1955,10 @@
 
       <toolbaritem id ="folder-location-container" title="&folderLocationToolbarItem.title;"
                    align="center" class="chromeclass-toolbar-additional">
-          <menulist id="locationFolders" class="folderMenuItem" label=" " width="170" crop="center">
-            <menupopup id="folderLocationPopup" class="folderLocationPopup" height="400" flex="1" 
-                       oncommand="OnLocationTreeSelect(this);"/>
-          </menulist>
+        <menulist id="locationFolders" class="folderMenuItem" label=" " context="folderPaneContext" width="170" crop="center">
+          <menupopup id="folderLocationPopup" class="folderLocationPopup" height="400" flex="1" 
+                     oncommand="OnLocationTreeSelect(this);"/>
+        </menulist>
       </toolbaritem>
       
       <toolbaritem id="mailviews-container" title="&mailViewsToolbarItem.title;" align="center" class="chromeclass-toolbar-additional">