Spectator view bug fix - preview window DPI awareness.

#91
Change preview window to a dropdown instead of a popup for better DPI awareness.
For best results, the windows taskbar will have to be hidden.

SpectatorView/Samples/SharedHolograms/Assets/Addons/HolographicCameraRig/Editor/PreviewWindow.cs

@@ -52,10 +52,11 @@ public static void ShowWindow()
             {
                 dim = new Vector2(Screen.currentResolution.width, Screen.currentResolution.height);
             }
+
             window = ScriptableObject.CreateInstance<PreviewWindow>();
             window.maxSize = new Vector2(6000, 4000);
             window.position = new Rect(pos, dim.Value);
-            window.ShowPopup();
+            window.ShowAsDropDown(new Rect(), dim.Value);
         }
         else
         {