Preview and compare optimization settings
Use the
document preview buttons to display the graphic as it would appear
in a web browser, based on optimization settings. You can preview
rollover and navigation behaviors, as well as animation.

The Original button and the document preview buttons
The preview displays the total size, estimated download time,
and file format of a document. The estimated download time is the
average amount of time it would take to download all the slices
and states on a 56K modem. The 2-Up and 4-Up views display additional
information that varies depending on the file type selected.
You can optimize an entire document or only selected slices while
viewing a preview. The slice overlay helps you differentiate the
slices currently being optimized from the rest of the document.
Preview a graphic based on the current optimization settings
Click the Preview button in the upper left of the
document window.
Note: Click Hide Slices

in
the Tools panel to hide slices and slice guides while previewing.
Compare views with different optimization settings
Click the 2-Up or 4-Up button
in the upper left of the document window.
Click one of the split-view previews.
Enter settings in the Optimize panel.
Select the other previews and specify different optimization
settings for each preview.
When you select 2-Up or 4-Up view,
the first split-view displays the original Fireworks PNG document
so that you can compare it with optimized versions. You can switch
this view with another optimized version.
Switch any optimized view to the original view in 2-Up or 4-Up mode
Select an optimized view.
From the Preview pop-up menu at the bottom of the preview
window, select Original (No Preview).
Switch the original view to an optimized view in 2-Up or 4-Up mode
Select the view containing the original.
From the Preview pop-up menu, select Image Preview.
Hide or show the slice overlay
Select View > Slice Overlay.