Fix old Unity Editor compatibility

Author: lawwong

Assets/HTC.UnityPlugin/ViveInputUtility/Scripts/Editor/VRPlatformSettings/OpenXRDesktopSettings.cs

@@ -110,6 +110,7 @@ private static void SetOpenXRFeatureGroupEnable(BuildTargetGroup target, string
 
         private static bool ShowXRPluginManagementSection()
         {
+#if VIU_OPENXR
             try
             {
                 var projectSettingsType = Assembly.GetAssembly(typeof(SettingsProvider)).GetType("UnityEditor.ProjectSettingsWindow");
@@ -123,6 +124,9 @@ private static bool ShowXRPluginManagementSection()
                 return false;
             }
             return true;
+#else
+            return false;
+#endif
         }
     }
 }

Assets/HTC.UnityPlugin/ViveInputUtility/Scripts/Editor/VRPlatformSettings/WaveVRSettings.cs

@@ -207,7 +207,7 @@ public override void OnPreferenceGUI()
 
 #if !UNITY_5_6_OR_NEWER || UNITY_5_6_0 || UNITY_5_6_1 || UNITY_5_6_2
                     GUI.enabled = false;
-                    ShowToggle(new GUIContent(s_title.text, s_title.tooltip + ". Unity 5.6.3 or later version required."), false, GUILayout.Width(toggleWidth));
+                    ShowToggle(new GUIContent(s_title.text, s_title.tooltip + ". Unity 5.6.3 or later version required."), false, GUILayout.Width(wvrToggleWidth));
                     GUI.enabled = true;
 #else
                     if (activeBuildTargetGroup != BuildTargetGroup.Android)