Introduction

ExplorerTreeView is an ActiveX control that may be used as a common treeview as well as for shell-browsing. It is optimized for Visual Basic 6.0, but should also work in any other environment that supports COM controls.

Basics

The control superclasses the native treeview window class of Windows: SysTreeView32. Although I tried to wrap all features of this window class (status: Windows 10), some things may be missing. In these cases you usually may use the Win32 API and handle the control as a native treeview window. One of my goals was it to create a treeview control that may be controlled via API as well as via the classes that I implemented.
The control's label-edit control is a native edit window of Windows and it may be controlled via API, too.

Conventions

An "item button" is the "+"/"-" button that can be displayed next to an item to indicate that this item has sub-items. It is also referred to as "expando" to match Microsoft Windows SDK.

Requirements

ExplorerTreeView Unicode runs on the following operating systems:

Windows XP (SP3 or later)
Windows Server 2003 (SP2 or later)
Windows Vista (SP2 or later)
Windows Server 2008 (SP2 or later)
Windows 7 (SP1 or later)
Windows Server 2008 R2 (SP1 or later)
Windows 8
Windows Server 2012
Windows 8.1
Windows Server 2012 R2
Windows 10
Windows Server 2016
Systems supported by Wine (Wine is a Win32 subsystem for alternative operating systems) - limited support
ReactOS (a free Windows XP clone) - limited support

Some features have additional requirements which are mentioned in the affected feature's documentation.
Limited support means, that I won't invest much work to support those systems. If a feature works on a system tagged with "limited support" - fine; if it does not and it's easy to fix, I'll fix it, but if it's difficult to fix, I probably won't fix it. Also I will test the control much less on those systems.

Support

There's no entitlement to support. Period. However, you have good chances to get help if you post your questions on GitHub or in the forums.
Also the project is open source, so feel free to have a look at the source code. You may modify it, but please consider sharing your changes with the rest of the world.

License

     MIT License

     Copyright (c) 2002-2019 Timo Kunze

     Permission is hereby granted, free of charge, to any person obtaining a copy
     of this software and associated documentation files (the "Software"), to deal
     in the Software without restriction, including without limitation the rights
     to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     copies of the Software, and to permit persons to whom the Software is
     furnished to do so, subject to the following conditions:

     The above copyright notice and this permission notice shall be included in all
     copies or substantial portions of the Software.

     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     SOFTWARE.

Acknowledgements

Thanks go to:

Wine Headquarters, because Wine helped me a lot on understanding how Windows is working.
Microsoft, for ATL, WTL and Visual Studio - great libraries and a great IDE
Igor Tandetnik, for his great help on learning ATL and WTL
Dimitri van Heesch, for Doxygen
Nikos Bozinis, for his awesome help with the Vista drag'n'drop stuff.
Christian Lütgens, for his great work as beta-tester and for his help when I needed a 2nd opinion on some decisions.
All donators
For great music: Heaven Shall Burn, Arch Enemy, Machine Head, Trivium, Deadlock, Draconian, Soulfly, Delain, Lacuna Coil, Ensiferum, Epica, Sirenia, Tristania, Nightwish, Battlelore, Amon Amarth, Volbeat, Guns N' Roses

FAQ

1. Why is the Font property ignored?
It isn't. My controls have a property UseSystemFont which defaults to True. This property tells the control to use the system font rather than the font set by the Font property.
Why is this property's default True? Well, if I set system wide settings (like fonts) I expect all applications to follow them. Unfortunately ignoring system wide settings seems to be trendy, so see my decision as an educational measure.

2. Why is event xyz not fired?
Firing an event is relative time-consuming, even if the event isn't handled by the application at all. Therefore I implemented a DisabledEvents property which can be used to deactivate certain events.
By default many events are deactivated.

3. The control doesn't seem to have full Unicode support if it is used in Visual Basic 6. Why?
The forms, that Visual Basic 6 is creating, are ANSI windows. Therefore they force the control's underlying native treeview window class to use ANSI messages when communicating with the form. This breaks Unicode support in some situations. To work around this problem, the WM_NOTIFYFORMAT message must be reflected back to the control.
In Visual Basic, you must subclass the control's container window and send WM_NOTIFYFORMAT back to the window that it was sent for. In C++, message reflection works similar. The sample projects teach you how to reflect the message.

4. Why can't I compare TreeViewItem objects using VB's Is operator?
The Is operator compares the objects by there memory address. To keep memory usage low and to ease internal item management, ExplorerTreeView creates objects, that wrap items or item collections, on the fly. Therefore you'll get different objects (with different addresses) for the same item. Because of the different addresses the Is operator handles the items as different ones.
To compare items, you should use the items' handles or IDs.