BrightSign Object Reference Manual (FW 5.1) - Manual (Page 95)

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The top 8 bits of the color value are "alpha," affecting both the foreground text color and the widget background color.
Zero is equivalent to fully transparent and 255 to fully non-transparent. This feature allows effects similar to subtitles. For
example, you can create a semi-transparent black box containing text over video.
Modes 0 and 1 are useful for displaying RSS feeds and ticker-type text. However, for dynamic data where immediate
screen updates are required, mode 2 is more appropriate. Mode 2 allows text to be drawn immediately to the screen.