It takes me quite a while for me to figure out how to clone my screen to the projector. The default setting (two separate screens) may be reasonable for power point presentation. But I would like to take advantage of the stylus during my presentation. Cloning the display is of course a better choice for tablet like notebook when doing a presentation.
Anyway, the command is simply
xrandr --output LVDS1 --auto --output VGA1 --auto --same-as LVDS1
I assume that the same command will work for other tablet notebook. The device’s names may be different though. One can however find them by simply running xrandr without any argument.