I'd vote for dropping support for lower than 24 bit.
Cool.
Really, the only thing holding me back is the knowledge that sometimes people will deliberately run their desktop in 16-bit to save memory, or (on older video cards or on cheap motherboard-embedded video chips) to achieve higher resolutions than are available in the 24-bit mode.
Then again, the target market for this applet is pretty small, so I could be wasting my time by trying to code in support for something no one will ever use.