https://learn.microsoft.com/en-us/answers/questions/5860976/teams-app-header-still-visible-despite-isfullscree
Teams App Header Still Visible Despite isFullScreen: true Configuration - Microsoft Q&A
I have set "isFullScreen": true in the app manifest; however, after uploading the app in the test environment, the default header (Home/About) is still visible...
teams app
https://www.php.net/manual/uk/ui-window.isfullscreen.php
PHP: UI\Window::isFullScreen - Manual
Full Screen Detection
phpuiwindowmanual