<p>I'm working on a solution that contains multiple projects targeting Windows Mobile 5 and standard Windows applications.</p>

<p>Lately when opening up a form in designer the common UI controls (textbox, button, label, etc etc...) have vanished leaving only the controls defined within the project.</p>

<p>Resetting the toolbox has no effect.  A google search suggested deleting the toolbox temp files in the <code>Local Settings\Application Data\Microsoft\VisualStudio\9.0</code>, however this was only successful in bringing back the default controls for Windows Mobile 5.  The WinForms controls are still mysteriously missing.</p>

<p>Also, if I right-click and <em>Select All</em> on the toolbox, all of the WinForms controls do in fact come up, however they're all grayed out.</p>

<p>Has anyone else experienced this?</p>

I've noticed this exact same thing for regular WinForms as well. I can't speak to mobile applications but in regular winforms this has a tendency to happen.
I believe it's actually a bug in Visual Studio.
There are some things you can do (again, for WinForms. I'm not sure about mobile) with adding attributes to your control. Such as:
```
```
[ToolboxBitmap(typeof(MyControl), "MyControlBitmap")]
```
```
There are some other useful related things on this site:
http://en.csharp-online.net/Design-Time_Integration-Attributes