Anchor.None - Controls moved after Page show

Hello,

we used a Page and placed a Panel on it with Anchor.None.

The Panel should alway center of the page (like a Web Page), no matter how large the browser is.

In principle, it works, but the controls are moved after the page is shown.

See sample, run it. Page is displayed, panel moves depending on the size of the browser window.

Can this be prevented?

Greetings

Ralf