What would be some functional usages for the transparency capabilities? I'm a little opaque on the use of it....

look at this image

since the buttons are rounded and there is a background image the user needed to create each button so that at each corner there is part of the background.

same for the cursor buttons on

transport buttons on

also by creating bitmaps that only look right in the right place you need to be extra careful on placement of the buttons.

plus if you use the same button on different backgrounds (or even if you look at the first example, on the same background but where the background changes) all you need to create is one bitmap so you save memory.

Thanks. So are you saying that this is an EDGE transparency feature for blending edges?

It isn't specific to edges - *any* pixels which are in the "transparent" colour will be transparent. You're right that it's most useful for blending the edges of bitmaps, though. As Anthony said, the big deal is that it means your button bitmaps don't have to have edges which match the background.

Your comment made me think of something else.

there is no way to make a button with two lines of text.

the work arounds are
a) make a button where the text is part of the bitmap icon
b) divide the bitmap icon in two and then have two buttons that look like one (this is the method I have used.

with the transparency you could actually use two frames and a single button on top that is mostly transparent.

Ok, Thanks. So it is like chromakey in video where one color is transparent. In this case it would be one of the 16 shades.

Exactly. You can pick which shade is treated as transparent, or you can tell it to automatically use the shade of the top-left pixel, which is nice when you want to eliminate the background colour surrounding a button.

But you need to make sure that what ever color you pick is only used where you want transparency