How to detect tablet mode

Question

I'm using the following code to detect if a user is in tablet mode or not. I'm on a Surface Pro and when I decouple the keyboard and make the PC into a tablet, IsTabletMode returns true (which it should.) When I use the "Tablet Mode" button without decoupling the screen, IsTabletMode always returns false. Has anyone experienced this and How can I resolve it?

/*
 * Credit to Cheese Lover
 * Retrieved From: http://stackoverflow.com/questions/31153664/how-can-i-detect-when-window-10-enters-tablet-mode-in-a-windows-forms-applicatio
 */
public static class TabletPCSupport
{
   private static readonly int SM_CONVERTIBLESLATEMODE = 0x2003;
   private static readonly int SM_TABLETPC = 0x56;

   private Boolean isTabletPC = false;

   public Boolean SupportsTabletMode { get { return isTabletPC; }}

   public Boolean IsTabletMode 
   {
       get
       {
           return QueryTabletMode();
       }
   }

   static TabletPCSupport ()
   {
        isTabletPC = (GetSystemMetrics(SM_TABLETPC) != 0);
   }

   [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "GetSystemMetrics")]
   private static extern int GetSystemMetrics (int nIndex);

   private static Boolean QueryTabletMode ()
   {
       int state = GetSystemMetrics(SM_CONVERTIBLESLATEMODE);
       return (state == 0) && isTabletPC;
   }
}

Answer 1

Edit 2: The SM_TABLETPC is only supported by Windows XP Tablet PC Edition and Windows Vista. There doesn't seem to be any reference to Windows 10 here: https://msdn.microsoft.com/en-us/library/windows/desktop/ms700675(v=vs.85).aspx

You can use this: GetSystemMetrics(SM_CONVERTIBLESLATEMODE). A “0” returned means it is in tablet mode. A “1” returned means it is in non-tablet mode. https://software.intel.com/en-us/articles/how-to-write-a-2-in-1-aware-application

Can you replace the QueryTabletMode method with this:

   private static Boolean QueryTabletMode ()
   {
       int state = GetSystemMetrics(SM_CONVERTIBLESLATEMODE);
       return (state == 0);
   }

Edit: You might need to check this periodically as there's no event to see if the PC's tablet mode was turned on