UnityEditor.EditorApplicationLayout.IsInitializingPlaymodeLayout C# (CSharp) Method

        internal static bool IsInitializingPlaymodeLayout()
        {
            return (m_GameView != null);
        }

 private void OnLostFocus()
 {
     if (!EditorApplicationLayout.IsInitializingPlaymodeLayout())
     {
         this.AllowCursorLockAndHide(false);
     }
     InternalEditorUtility.OnGameViewFocus(false);
 }