R – Compact framework equivalent of traceview

It's probably better to not uninstall, and if it's on the device in ROM you can't uninstall it anyway.

There are a couple options available to you.

1. The different CF versions coexist fine, so you can install the older version and leave 3.5 on it.
2. The CF can be set for compatibility mode. That means you can tell just a single app compiled against an old version use the 3.5 runtimes in compatibility mode or you can set that device-wide so all older CF apps will run agains the 3.5 EE in compatibility mode.

For online resources discussing configuration files and compatibility mode, see these links:

• MSDN Article on Configuration File Settings
• MSDN Article on Configuring Runtime Versions
• David Kline's blog on Compatibility Mode
• The CF 3.5 Power Toys (includes an app for setting configurations)

Note: I forgot to mention in the original response that using option #2 (running against CF 3.5) will very likely improve the performance of the app as well, since it will be running with the newest CLR.

Are you using WinForms? A lot of the controls implement a Site property which returns this type http://msdn.microsoft.com/en-us/library/system.componentmodel.isite.aspx is has a DesignMode property which you can use to check if it's in design mode or not.

In the void OnRender(...) method you can check this property if it's set or not and you can then draw depending on design time or not.

protected override void OnRender(...)
{
    if (this.Site != null && 
        this.Site.DesignMode) 
    {
        // Draw something...
    }
}

Check out this post about potentional problems with Site and the DesignMode property http://decav.com/blogs/andre/archive/2007/04/18/1078.aspx