DotNet application in FullScreen mode

Hello.
Since I have installed Sonoma in my iMac Intel, I have a problem using my DotNet Winforms Application.
My application is designed like this :
- no controlbox
- no maximized button
- no minimized button
=> CaptionBar is automatically removed.

If I put a button at the top of the form, and this form is located à 0,0, then no event clic is raised.

I think is in relation with the MacOs Menu because it's possible to clic a little lower.

Works fine on :
- MacBook Pro M1
- a physical Windows PC
- in my iMac intel on Windowed mode
- in my iMac intel on Fullscreen mode with ventura and older MacOs