Question: How can I know in a C#-Application, in which direction the screen of the mobile device is orientated? (i.e. horizontal or vertical).

Answer: 
Add a reference to Microsoft.WindowsCE.Forms to your project. Then you can reference the 
Microsoft.WindowsCE.Forms.**SystemSettings.ScreenOrientation** property, which will give you what you need.

Incidentally, you can set this property, so it can be used to set your screen orientation also.
you should add 2 Refrences to the project:
Microsoft.WindowsMobile
Microsoft.WindowsMobile.Status

then you can use this code for determine orientation:

```
int orientation=Microsoft.WindowsMobile.Status.SystemState.DisplayRotation;
if(orientation== 90 || orientation==-90 || orientation==270) //Landscape is 90 or -90 or 270
{
    //your code;
}
else
{
    //your code;
}

```