Event for orientation change done?

Im using a GetLastRect() in my ONGUI to figure out where I can place my 3D Logo on Screen. This works fine on PC but when I rotate my Tablet the Rotate seems to be too slow and the coordinates that I calculate are wrong.
Starting the game shows the logo right in place no matter what orientation I start with, but after the first rotate it is totally off.

So I wonder if there is something like an event in Unity that tells me when I can savely take the measurements of the GUILayout after the screen was rotated / orientation changed.

To draw 3D stuff within the GUI you need to do 2 things:

  1. Define a rect to draw. When using GUILayout use either GUILayoutUtility.GetRect or as you mentioned GetLastRect of another element.
  2. Use a disabled camera which shows your 3D stuff.
  3. Draw the camera manually during the Repaint event by calling camera.Render(). Don’t forget to set the pixelRect of your camera to your drawing rect from point 1.