imageUrl
The image URL or image virtual path to which to add its page(s) as thumbnail(s). Each page will be added as a new thumbnail.
firstPage
The 1-based index of the first page to load.
lastPage
The 1-based index of the last page to load. Must be greater than or equal to firstPage. You can pass -1 to load from firstPage to the last page in the file.
This example initializes the WebThumbnailViewer control and connect it to a WebImageViewer control, then loads "multipage.tif" file into it, and select the first thumbnail to display its image into the WebImageViewer control.