Background Image for Preview
Preview looks like the real page, but the links leed to an oops dialog warning users of not yet saved topics. In addition, a background with a "PREVIEW" watermark is shown to have visual clue that you are previewing a topic. You can change the background image by specifying the name of an attached background image file in the PREVIEWBGIMAGE variable in the TWikiPreferences.
Remarks:
You also could attach a new image file to this topic.
You can override the PREVIEWBGIMAGE preference variable in your personal home page.