get exclusive keyword

    T GetKeyword<T>(Dictionary<T, string> keywords) where T : Enum
    {
        T[] types = (T[])Enum.GetValues(typeof(T));
        T toSet = types.ToList().Find(t => !keywords.Keys.Contains(t));
        foreach (KeyValuePair<T, string> kvp in keywords)
        {
            if (target.IsKeywordEnabled(kvp.Value)) toSet = kvp.Key;
        }
        return toSet;
    }
void KeywordDropdown<T>(Dictionary<T, string> keywords, T current,
        string displayName = null, string tooltip = null) where T : Enum
    {
        GUIContent label = new GUIContent(displayName, tooltip);
        EditorGUI.BeginChangeCheck();
        current = (T)EditorGUILayout.EnumPopup(label, current);
        if (EditorGUI.EndChangeCheck())
        {
            foreach (KeyValuePair<T, string> kvp in keywords)
            {
                if (kvp.Key.Equals(current)) target.EnableKeyword(kvp.Value);
                else target.DisableKeyword(kvp.Value);
            }
        }
    }
    void KeywordDropdown<T>(Dictionary<T, string> keywords, string displayName = null,
        string tooltip = null) where T : Enum
    {
        T current = GetKeyword<T>(keywords);
        KeywordDropdown<T>(keywords, current, displayName, tooltip);
    }