Merge pull request #2303 from AvaloniaUI/fixes/x11-monitor-scaling-fullhd-and-below

Scaling of 1 on monitors >= FullHD

src/Avalonia.X11/X11Screens.cs

@@ -218,6 +218,7 @@ namespace Avalonia.X11
 
     class X11Screen
     {
+        private const int FullHDWidth = 1920;
         public bool Primary { get; }
         public string Name { get; set; }
         public PixelRect Bounds { get; set; }
@@ -247,6 +248,6 @@ namespace Avalonia.X11
         }
 
         public static double GuessPixelDensity(double pixelWidth, double mmWidth)
-            => Math.Max(1, Math.Round(pixelWidth / mmWidth * 25.4 / 96));
+            => pixelWidth <= FullHDWidth ? 1 : Math.Max(1, Math.Round(pixelWidth / mmWidth * 25.4 / 96));
     }
 }