You can run a Compact Framework application in regular Windows (maybe). There are two major potential problems with this, however.
First, because certain form and control properties present in the full framework are missing in the compact framework, your application will behave a bit oddly in Windows. For example, in the full framework forms have a StartPosition property which determines where the forms appear on the screen when they're first created. This property does not exist in the compact framework (for obvious reasons), so when you run your CF application in regular Windows, the forms pick up the default StartPosition value of WindowsDefaultLocation, which means that setting the form's Left and Top properties has no effect on where they appear, so the forms pop up wherever.
Second, any Windows API PInvoke calls in CF must reference "coredll", whereas the same calls in the full framework reference "user32", "winmm" etc. One way around this problem is to do something like this:
[DllImport("winmm.dll", EntryPoint="waveOutReset")]
private static extern int waveOutResetFULL(IntPtr hWaveIn);
[DllImport("coredll.dll", EntryPoint="waveOutReset")]
private static extern int waveOutResetCF(IntPtr hWaveIn);
public static int waveOutReset(IntPtr hWaveIn)
{
if (Environment.OSVersion.Platform == PlatformID.WinCE)
{
return waveOutResetCF(hWaveIn);
}
else
{
return waveOutResetFULL(hWaveIn);
}
}
There are other ways to do this, also.
Regarding the first set of problems, one solution is to set the properties that are missing in the compact framework via Reflection when the application is running in regular Windows. I think a better alternative is to encapsulate all the elements of your UI as UserControls, each one hosted on a single "master" UserControl that creates and disposes the other UserControl elements as needed. You can then host your single "master" UserControl on a single instance of a form.
By the way, I wrote an application that does exactly this (run in Windows and on Windows Mobile devices) for a major shipbuilder, and it is still in use. In fact, the ability of this application to run in both environments literally saved its life when the use of mobile devices in the shipyard was temporarily suspended for security reasons.