internal void OnGUI()
{
FitWindowToContent();
Rect windowRect = new Rect(m_BorderWidth, m_BorderWidth, position.width - 2 * m_BorderWidth, position.height - 2 * m_BorderWidth);
m_WindowContent.OnGUI(windowRect);
GUI.Label(new Rect(0, 0, position.width, position.height), GUIContent.none, "grey_border");
}