rem: drawing_mode=0; bitmap_background=NULL; bitmap_overlay=NULL;
add: draw_mode=B_OP_COPY; background=NULL; overlay=NULL;
context: LayerData(void)	{		pensize=1.0;		penlocation.Set(0,0);		drawing_mode=0;		bitmap_background=NULL;		bitmap_overlay=NULL;		highcolor.SetColor(0,0,0,255);		lowcolor.SetColor(255,255,255,255);		//SFont font;		//bool antialias_text;		scale=1.0;	};