Qemu can't display on fullscreen

[fnq3]

Previously, I run the qemu-system-x86_64 with options "--full-screen" , VM can display on the full screen.

But not on TC8, although with this parameter"--full-screen", but the output is still a window,  not full screen.
on tc9 too .

Why,Is this a BUG?



  I'm sorry, my English is very poor.