Only call GetDpiForWindow if it's actually available

apparently this is limited to windows 10 1607+

src/BizHawk.Client.EmuHawk/DisplayManager/DisplayManager.cs

@@ -11,6 +11,29 @@ namespace BizHawk.Client.EmuHawk
 {
 	public class DisplayManager : DisplayManagerBase
 	{
+		// this function requires at least windows 10
+		private static readonly unsafe delegate* unmanaged[Stdcall]<IntPtr, int> _getDpiForWindow;
+
+		static DisplayManager()
+		{
+			if (OSTailoredCode.IsUnixHost)
+			{
+				return;
+			}
+
+			var lib = OSTailoredCode.LinkedLibManager.LoadOrZero("user32.dll");
+			if (lib == IntPtr.Zero)
+			{
+				return;
+			}
+
+			unsafe
+			{
+				_getDpiForWindow = (delegate* unmanaged[Stdcall]<IntPtr, int>)
+					OSTailoredCode.LinkedLibManager.GetProcAddrOrZero(lib, "GetDpiForWindow");
+			}
+		}
+
 		private readonly Func<bool> _getIsSecondaryThrottlingDisabled;
 
 		private bool? _lastVsyncSetting;
@@ -51,12 +74,8 @@ namespace BizHawk.Client.EmuHawk
 
 		public override Size GetPanelNativeSize() => _presentationPanel.NativeSize;
 
-		protected override int GetGraphicsControlDpi()
-		{
-			return OSTailoredCode.IsUnixHost
-				? DEFAULT_DPI
-				: Win32Imports.GetDpiForWindow(_graphicsControl.Handle);
-		}
+		protected override unsafe int GetGraphicsControlDpi()
+			=> _getDpiForWindow == null ? DEFAULT_DPI : _getDpiForWindow(_graphicsControl.Handle);
 
 		protected override Point GraphicsControlPointToClient(Point p) => _graphicsControl.PointToClient(p);
 

src/BizHawk.Common/Win32/Win32Imports.cs

@@ -67,8 +67,5 @@ namespace BizHawk.Common
 
 		[DllImport("user32.dll", ExactSpelling = true)]
 		public static extern int TrackPopupMenuEx(IntPtr hmenu, TPM fuFlags, int x, int y, IntPtr hwnd, IntPtr lptpm);
-
-		[DllImport("user32.dll", ExactSpelling = true)]
-		public static extern int GetDpiForWindow(IntPtr hwnd);
 	}
 }