can i hide/delete this red part?

[piercashuang]

i dont know the name of this part so i cant google...i tried but i only find someinfo about menubar, but this is not menubar.So i have no concept of whats this and no idea how can i hide/delete it

[ChrisW67]

@piercashuang That red part is the standard window title bar (part of the frame) applied to top-level windows by whatever operating system/window manager you are using. You can suggest to Windows that you do not want this with the Qt::FramelessWindowHint.
window flag.

See also Window Flags Example.

[Ronel_qtmaster]

@piercashuang setWindowFlags(Qt::FramelessWindowHint);