If a action is called with no menu item the bradcrumbs navigation fail to give
the correct breadcrumb

_populate_admin_navigation(

'show_in_menu'=>true

for the Breadcrumbs navigation to work probebly with CmsAdminMenuItem
there schould be a key in CmsAdminMenuItem maybe called showinmenu

this key should be by default true for compatibility reason.

and in the method _populate_admin_navigation( there could be easaly called
'show_in_menu'=>$menuItem->showinmenu

it's better then

// if we only have a pending key, we use it... not ideal.
if( !$selected_key && $pending_selected_key ) $selected_key =
$pending_selected_key;