Add Win32 Methods to allow getting of MonitorInfo

src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs

@@ -850,6 +850,10 @@ namespace Avalonia.Win32.Interop
 
         [DllImport("user32.dll")]
         public static extern IntPtr MonitorFromWindow(IntPtr hwnd, MONITOR dwFlags);
+        
+        [DllImport("user32", EntryPoint = "GetMonitorInfoW", ExactSpelling = true, CharSet = CharSet.Unicode)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        public static extern bool GetMonitorInfo([In] IntPtr hMonitor, [Out] MONITORINFO lpmi);
 
         [return: MarshalAs(UnmanagedType.Bool)]
         [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
@@ -862,6 +866,23 @@ namespace Avalonia.Win32.Interop
             MONITOR_DEFAULTTONEAREST = 0x00000002,
         }
 
+        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
+        internal class MONITORINFO
+        {
+            public int cbSize = Marshal.SizeOf(typeof(MONITORINFO));
+            public RECT rcMonitor = new RECT();
+            public RECT rcWork = new RECT();
+            public int dwFlags = 0;
+
+            public enum MonitorOptions : uint
+            {
+                MONITOR_DEFAULTTONULL = 0x00000000,
+                MONITOR_DEFAULTTOPRIMARY = 0x00000001,
+                MONITOR_DEFAULTTONEAREST = 0x00000002
+            }
+        }
+
+
         public enum PROCESS_DPI_AWARENESS
         {
             PROCESS_DPI_UNAWARE = 0,