If you are using template scripts in your project go to the left recource pane in the World Editor (WED), where you find "Object, Views ... etc", select "Resources". Then go to the "Scripts" directory and select display00.wdl, right click and select "Customize". Set the video "Force Full/Window" to 1 (= on). Save. This will change the boot to full screen. If you don't use template scripts, you could follow the advice of Lion Ts, or use the c-script command
"video_switch (var res,var depth,var window)" to set the boot parameters.
hope this solves the question,
cheers,
tindust