@@TVirtualTreeCast
Necessary to make the header accessible.


@@TVTHeaderPopupOption.poAllowHideAll
Allows to hide all columns, including the last one.

@@TVTHeaderPopupOption.poOriginalOrder
Show menu items in original column order as they were added to the tree.

@@VTHeaderPopup.pas
The contents of this file are subject to the Mozilla Public License
Version 1.1 (the "License"); you may not use this file except in
compliance with the License. You may obtain a copy of the License at
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Alternatively, you may redistribute this library, use and/or modify it under the terms of the
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either version 2.1 of the License, or (at your option) any later version.
You may obtain a copy of the LGPL at http://www.gnu.org/copyleft/.

Software distributed under the License is distributed on an "AS IS"
basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
License for the specific language governing rights and limitations
under the License.

The Original Code is VTHeaderPopup.pas.

The Initial Developer of the Original Code is Ralf Junker <delphi@zeitungsjunge.de>. All Rights Reserved.

Modified 14 Sep 2003 by Mike Lischke <public@delphi-gems.com>.
  - Renamed event type name to be consistent with other event types (e.g. used in VT).
  - Added event for hiding/showing columns.
  - DoXXX method are now virtual.
  - Conditional code rearrangement to get back Ctrl+Shift+Up/Down navigation back.
Modified 31 Mar 2003 by Mike Lischke <public@delphi-gems.com>.
  Added a check for the PopupComponent property before casting it hardly to a Virtual Treeview. People might
  (accidentally) misuse the header popup.

Modified 20 Oct 2002 by Borut Maricic <borut.maricic@pobox.com>.
  Added the possibility to use Troy Wolbrink's Unicode aware popup menu. Define the compiler symbol TNT to enable it.
  You can get Troy's Unicode controls collection from http://home.ccci.org/wolbrink/tnt/delphi_unicode_controls.htm).

Modified 24 Feb 2002 by Ralf Junker <delphi@zeitungsjunge.de>.
  Fixed a bug where the OnAddHeaderPopupItem would interfere with poAllowHideAll options.
  All column indexes now consistently use TColumnIndex (instead of Integer).

Modified 23 Feb 2002 by Ralf Junker <delphi@zeitungsjunge.de>.
  Added option to show menu items in the same order as the columns or in original order.
  Added option to prevent the user to hide all columns.

Modified 17 Feb 2002 by Jim Kueneman <jimdk@mindspring.com>.
  Added the event to filter the items as they are added to the menu.