BriskBard, CEF4Delphi, WebView4Delphi, WebUI4Delphi and WebUI4CSharp

I haven't tried but InvalidateRect with TChromiumWindow.ChildWindowHandle as the first parameter should work.

I need this kind of method too please

Have you tried setting the visibility to False in the panels below the top panel ?
When you need to switch to a different panel you only need to set its visibility to True again, call the bringtofront function and set the focus in the browser.