Identifies the different modes of image background drawing.

Values:

IG_DSPL_BACKGROUND_NONE	The background is disabled, and ImageGear does not fill this area.
IG_DSPL_BACKGROUND_UNDER_IMAGE	The image's transparent pixels are drawn with current background color and background brush. The area outside of Displayed Image Rectangle is not affected.
IG_DSPL_BACKGROUND_BEYOND_IMAGE	The transparent pixels that are outside of Displayed Image Rectangle are drawn with current background color and background brush.
IG_DSPL_BACKGROUND_EVERYWHERE	The background is under the image and beyond the image.