I'm not sure if I have a different version or something but what I have, the triangle is just a simple Triangle call to draw on screen.
Well, I remember he made a compatibility version that probably removed that surface so it would work faster in the then dx8 and GL drivers.
It used to draw gradient rectangles to the screen, but the last version just loads a pre-generated image, with the generating code commented out.
/*	GradientRectangle(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, COL_LIGHT_GREY, COL_DARK_GREY, COL_BLACK, COL_DARK_GREY);
	var temp_back = GrabSurface(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
*/	
	// DEBUG
/*	temp_back.save("bgi_" + SCREEN_WIDTH + "_" + SCREEN_HEIGHT + ".png");
	Abort("bgi_" + SCREEN_WIDTH + "_" + SCREEN_HEIGHT + ".png");
*/	
function PreRenderBackground ()
{
/*	// Draw the main background
	GradientRectangle(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, COL_LIGHT_GREY, COL_DARK_GREY, COL_BLACK, COL_DARK_GREY);
	
	// Draw the top bars
	GradientRectangle(0, 0, SCREEN_WIDTH, mainFont.getHeight(), COL_LIGHT_GREY, COL_LIGHT_GREY, COL_DARK_GREY, COL_DARK_GREY);
	GradientRectangle(0, mainFont.getHeight(), SCREEN_WIDTH, mainFont.getHeight(), COL_LIGHT_GREY, COL_LIGHT_GREY, COL_DARK_GREY, COL_DARK_GREY);
	
	// Clock space
	Rectangle(SCREEN_WIDTH - mainFont.getStringWidth(" 00:00:00"), 0, mainFont.getStringWidth(" 00:00:00"), mainFont.getHeight(), CreateColor(0, 0, 0, 32));
	
	// Draw the Sphere icon box
	GradientRectangle(0, 0, sphereIcon.width, sphereIcon.height, COL_LIGHT_GREY, COL_LIGHT_GREY, COL_DARK_GREY, COL_DARK_GREY);
	
	// Draw the bottom bar
	Rectangle(0, SCREEN_HEIGHT - mainFont.getHeight(), SCREEN_WIDTH, mainFont.getHeight(), CreateColor(0, 0, 0, 128));
	
	// Store it and clear it
	background = GrabSurface(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
	Rectangle(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, COL_BLACK);
*/	
	// DEBUG
/*	background.save("bg_" + SCREEN_WIDTH + "_" + SCREEN_HEIGHT + ".png");
	Abort("bg_" + SCREEN_WIDTH + "_" + SCREEN_HEIGHT + ".png");
*/	
	
	// Load the appropriate background instead
	background = LoadSurface("bg_" + SCREEN_WIDTH + "_" + SCREEN_HEIGHT + ".png");
	
	return;
}