NM_TREEVIEW* tv = (NM_TREEVIEW *)lParam;
wxTreeItemData *data = (wxTreeItemData *)tv->itemOld.lParam;
delete data; // may be NULL, ok
NM_TREEVIEW* tv = (NM_TREEVIEW *)lParam;
wxTreeItemData *data = (wxTreeItemData *)tv->itemOld.lParam;
delete data; // may be NULL, ok