<p>When my application opens too many windows the taskbar groups them into one button. Each window has its own icon, but the grouping icon is the default "unknown"-kind icon.</p>

<p>How can I set the grouping icon?</p>

The taskbar group icon can be set in the registry on a per application basis.
For explorer, this would be here:
```
```
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Applications\explorer.exe]
"TaskbarGroupIcon"="C:\Windows\Explorer.exe,13"
```
```