MenuStrip "flickers" when switching between MDI childs

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C#

WinForms

menu

forms

GUI

MDI

Hey guys, I hope you can help me out, I cannot find a solution for the following problem:
We have on MainMenuStrip. And when a mdi child is opend, it's icon is shown on the left side of this. Everything is fine so far.
But when I have two mdi childs and want to switch between them, the "mdi icon" on the left disappears for a very short time and then the icon of the new child is shown.
This leads to some very uncomfortable flickering because all the menu items move to the left for very short time and then jump back to the right because of this mdi icon.

Do you have any idea how to avoid the disappearing of the mdi icon during mdi child change?

Thanks in advance,
Markus