The auto resize on XFCE feature seems like to ignore the window control and video control when resizing video with the same resolution on display even with prevent main window to get outside of the screen ( 1080p video on 1080p screen)
This is not seems to be the case on Gnome.
XFCE 4.14
Gnome with the same setting
This is on manjaro with xfce 4.14.
You can see that on the gnome side, the window and video control are still present when auto resizing, but on xfce both of the control went outside of the screen.
xfce is my preferred desktop environment now so i hope fixes will be coming.
Thanks for this program, the best replacement for mpc / klite from windows on linux for me, because it can be configured to act the same behaviour like this auto resize features which behave different on other linux video players and not configurable.