Sometimes message from exception that occurred inside .Net CF classes doesn’t look handly at all:

An error message cannot be displayed because an optional resource assembly containing it cannot be found.

The thing is that error messages are actually in the resource assembly which is not installed on the device. So to fix the problem you just need to install this assembly:

1. Navigate to CompactFramework folder in the SDK which is “%Program Files%\Microsoft.NET\SDK\CompactFramework”.
2. Navigate to Diagnostics folder under desired .Net CF version (“v3.5\WindowsCE\Diagnostics” for 3.5 or “v2.0\WindowsCE\Diagnostics” for 2.0).
3. Copy resource CAB file to device according to the language you want and install it.

Below is a snapshot that shows how to change screen orientation from normal to 90 degree rotated or from 90 degree back to normal depending on current screen state:

if (SystemSettings.ScreenOrientation == ScreenOrientation.Angle0) {
	SystemSettings.ScreenOrientation = ScreenOrientation.Angle90;
}
else {
	SystemSettings.ScreenOrientation = ScreenOrientation.Angle0;
}

To make this code compile don’t forget to import Microsoft.WindowsCE.Forms namespace.

New home screen available in Windows Mobile 6.5 should be refreshed differently for Professional and Standard editions of OS. It can be done using the same API methods as for earlier versions of Windows Mobile.

For Professional edition it can be done like this:

[DllImport("coredll.dll")]
private static extern IntPtr PostMessage(int hWnd, int msg, uint wParam, uint lParam);

private const int HWND_BROADCAST = 0xFFFF;
private const int WM_WININICHANGE = 0x001A;

public static void Refresh() {
	PostMessage(HWND_BROADCAST, WM_WININICHANGE, 0xF2, 0);
}

For Standard edition the trick is to provide correct GUID to API. This GUID can be found in SlidingPanel.home.xml file located in “\Application Data\Home” folder. Here is the code:

[DllImport("aygshell.dll")]
public extern static uint SHOnPluginDataChange(ref Guid clsid);

public static void Refresh() {
	Guid guid = new Guid("{E9267CAB-02EE-4f37-8216-6BF6A8FF5A71}");
	SHOnPluginDataChange(ref guid);
}