I have a layout with a few regions and I am using a background image. In the layout preview the layout displays properly allowing the background image to pass through the region. In the Windows client (1.7.1) there is a white box the size of the region which blocks the layout background.
The regions have text and flash modules.
I would upload images but I can’t as a new user.
The screenshot is from the layout designer. All regions have a white background in the designer so you can see where they are.
If it’s white on the Player too then your flash object’s background is set to be white rather than transparent, so you’d need to modify your flash file.