first error:
Assets/6by7/ProGrids/Scripts/Editor/ProGrids_GUI.js(108,56): BCE0004: Ambiguous reference ‘constructor’: UnityEngine.GUIContent.constructor(UnityEngine.Texture, String), UnityEngi
Second error:
Assets/6by7/ProGrids/Scripts/Editor/ProGrids_GUI.js(114,55): BCE0004: Ambiguous reference ‘constructor’: UnityEngine.GUIContent.constructor(UnityEngine.Texture, String), UnityEngine.GUIContent.constructor(String, String).
Third error:
Assets/6by7/ProGrids/Scripts/Editor/ProGrids_GUI.js(120,55): BCE0004: Ambiguous reference ‘constructor’: UnityEngine.GUIContent.constructor(UnityEngine.Texture, String), UnityEngine.GUIContent.constructor(String, String).