preferences fixes and dropdown styles

Assets/PreferenceData.cs

@@ -0,0 +1,37 @@
+using System.IO;
+using UnityEngine;
+
+[System.Serializable]
+public class PreferenceData {
+    // Preference Fields
+    public int themeIndex;
+
+    // Others
+    string _path;
+
+    public PreferenceData(string path) {
+        _path = path;
+        themeIndex = 0;
+    }
+
+    public PreferenceData Load() {
+        try {
+            string json = File.ReadAllText(_path);
+            JsonUtility.FromJsonOverwrite(json, this);
+            return this;
+        } catch {
+            // file doesn't exist yet
+            return Save();
+        }
+    }
+
+    public PreferenceData Save() {
+        File.WriteAllText(_path, JsonUtility.ToJson(this));
+        return this;
+    }
+}
+
+public interface IPreferenceData {
+    PreferenceData LoadPreferences();
+    PreferenceData SavePreferences();
+}