I have often noticed when I save my images as transparent GIF files, if they have white text the white turns transparent (which is NOT what I want).
A common type of image I use is a rounded green button with white text. Since I use these buttons on different color backgrounds, I like to save it as a transparent GIF.
Here is the correct method for saving a transparent GIF with white text in Fireworks:
1. File>Export Preview
2. Choose GIF file type
3. Choose matte color
4. Now you will see that they white text may have turned transparent. In order to turn it back to white:
5. Select Alpha Transparency
6. Click on the eye dropper with the minus sign
7. Click on the space you want to remain white
8. If it looks ok, choose export, and you’re done
For a detailed explanation of this process check out http://www2.sfasu.edu/msri/Helpdesk/S14_transparent_gif.htm