Dev/build window improvements (#853)

# XRTK - Mixed Reality Toolkit Pull Request

## Overview
<!-- Please provide a clear and concise description of the pull request. -->
misc build window updates.

Editor/BuildPipeline/BuildDeployWindow.cs

@@ -77,10 +77,7 @@ private void OnEnable()
             Assert.IsNotNull(UnityPlayerBuildTools.BuildInfo);
         }
 
-        private void OnFocus()
-        {
-            platforms.Clear();
-        }
+        private void OnFocus() => platforms.Clear();
 
         private void OnGUI()
         {
@@ -137,7 +134,7 @@ private void OnGUI()
 
             if (GUILayout.Button("Open Unity Build Window", GUILayout.Width(176), GUILayout.ExpandWidth(true)))
             {
-                GetWindow(Type.GetType("UnityEditor.BuildPlayerWindow,UnityEditor"));
+                GetWindow(Type.GetType($"{nameof(UnityEditor)}.{nameof(BuildPlayerWindow)},{nameof(UnityEditor)}"));
             }
 
             EditorGUILayout.EndHorizontal();

Editor/BuildPipeline/BuildInfo.cs

@@ -15,45 +15,6 @@
 
 namespace XRTK.Editor.BuildPipeline
 {
-    [CustomEditor(typeof(BuildInfo), true)]
-    public class BuildInfoInspector : UnityEditor.Editor
-    {
-        private SerializedProperty autoIncrement;
-        private SerializedProperty bundleIdentifier;
-        private SerializedProperty install;
-
-        private BuildInfo buildInfo;
-
-        protected void OnEnable()
-        {
-            autoIncrement = serializedObject.FindProperty(nameof(autoIncrement));
-            bundleIdentifier = serializedObject.FindProperty(nameof(bundleIdentifier));
-            install = serializedObject.FindProperty(nameof(install));
-
-            buildInfo = (BuildInfo)target;
-        }
-
-        /// <inheritdoc />
-        public override void OnInspectorGUI()
-        {
-            serializedObject.Update();
-
-            EditorGUI.BeginChangeCheck();
-            EditorGUILayout.PropertyField(bundleIdentifier);
-
-            if (EditorGUI.EndChangeCheck())
-            {
-                var buildTargetGroup = UnityEditor.BuildPipeline.GetBuildTargetGroup(buildInfo.BuildTarget);
-                PlayerSettings.SetApplicationIdentifier(buildTargetGroup, bundleIdentifier.stringValue);
-            }
-
-            EditorGUILayout.PropertyField(autoIncrement);
-            EditorGUILayout.PropertyField(install);
-
-            serializedObject.ApplyModifiedProperties();
-        }
-    }
-
     [RuntimePlatform(typeof(WebGlPlatform))]
     [RuntimePlatform(typeof(WindowsStandalonePlatform))]
     public class BuildInfo : ScriptableObject, IBuildInfo

Editor/BuildPipeline/BuildInfoInspector.cs

@@ -0,0 +1,46 @@
+// Copyright (c) XRTK. All rights reserved.
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using UnityEditor;
+
+namespace XRTK.Editor.BuildPipeline
+{
+    [CustomEditor(typeof(BuildInfo), true)]
+    public class BuildInfoInspector : UnityEditor.Editor
+    {
+        private SerializedProperty autoIncrement;
+        private SerializedProperty bundleIdentifier;
+        private SerializedProperty install;
+
+        private BuildInfo buildInfo;
+
+        protected void OnEnable()
+        {
+            autoIncrement = serializedObject.FindProperty(nameof(autoIncrement));
+            bundleIdentifier = serializedObject.FindProperty(nameof(bundleIdentifier));
+            install = serializedObject.FindProperty(nameof(install));
+
+            buildInfo = (BuildInfo)target;
+        }
+
+        /// <inheritdoc />
+        public override void OnInspectorGUI()
+        {
+            serializedObject.Update();
+
+            EditorGUI.BeginChangeCheck();
+            EditorGUILayout.PropertyField(bundleIdentifier);
+
+            if (EditorGUI.EndChangeCheck())
+            {
+                var buildTargetGroup = UnityEditor.BuildPipeline.GetBuildTargetGroup(buildInfo.BuildTarget);
+                PlayerSettings.SetApplicationIdentifier(buildTargetGroup, bundleIdentifier.stringValue);
+            }
+
+            EditorGUILayout.PropertyField(autoIncrement);
+            EditorGUILayout.PropertyField(install);
+
+            serializedObject.ApplyModifiedProperties();
+        }
+    }
+}

Editor/MixedRealityPreferences.cs

@@ -317,6 +317,8 @@ public static IMixedRealityPlatform CurrentPlatformTarget
 
                     if (currentPlatformTarget == null)
                     {
+                        var possibleBuildTargets = new List<IMixedRealityPlatform>();
+
                         foreach (var availablePlatform in MixedRealityToolkit.AvailablePlatforms)
                         {
                             if (availablePlatform is AllPlatforms ||
@@ -330,11 +332,18 @@ public static IMixedRealityPlatform CurrentPlatformTarget
                             {
                                 if (EditorUserBuildSettings.activeBuildTarget == buildTarget)
                                 {
-                                    currentPlatformTarget = availablePlatform;
-                                    return currentPlatformTarget;
+                                    possibleBuildTargets.Add(availablePlatform);
                                 }
                             }
                         }
+
+                        Debug.Assert(possibleBuildTargets.Count > 0);
+
+                        currentPlatformTarget = possibleBuildTargets.Count == 1
+                            ? possibleBuildTargets[0]
+                            : possibleBuildTargets.FirstOrDefault(p => p.PlatformOverrides == null ||
+                                                                       p.PlatformOverrides.Length == 0);
+                        return currentPlatformTarget;
                     }
                 }