if (!G_Assocs[G_ActiveAssocID].TreeView._collections[CollectionID]) return true;
if (G_Assocs[G_ActiveAssocID].TreeView._collections[CollectionID].obj) var collection_message_list = G_Assocs[G_ActiveAssocID].TreeView._collections[CollectionID].obj;
else return true;
wheel_lock = true;
event.cancelBubble = true;
var message_counter_value = collection_message_list.Method0('M_GetCount');
var items_per_page = external.Method1('M_GetGlobalOption', 'ItemsPerPage');
if (message_counter_value > items_per_page)
{
var collection_node = G_Assocs[G_ActiveAssocID].TreeView.root._children[CollectionID];
var first_msg_index = collection_message_list.Method0('M_GetFirstVisibleMessageIndex');
var collection_container = document.getElementById('Assoc_'+AssocID).all[MsgCollectionObjID+'_container']; if (collection_container.children == null) return;