What's the most efficient way to create a semi-transparent overlay covering entire viewer window?

See title... Background: I want to show an image but have the viewer "greyed out" (similar to what happens when you open light/shadow box, etc.)...

Thanks!

PS: I've tried this

<plugin name="overlay" url="black_pixel.gif" alpha="0" visible="false" zorder="9" align="center" width="100%" height="100%" capture="false" />

But its animation (when opacity-tweened from say 0 to 0.8) is quite jerky... Any way to get this smoother?

Thanks!

Ok, did some more experimentation. The sluggishness seems to relate to the resizing of the single pixel gif. If I create a gif of 2562 x 1602 pixels (just a tad larger than the biggest "regular" screen resolution), it's still only about 3kb file size, but fading in and out is much, much smoother...

Ah, bummer, not so smooth after all ... the miniute there are a couple of animated hotspots the tweening just becomes very slow...

Klaus — is there any better way? It'd be handy to be able to set a background for a <plugin> . . .