Summary
By default, the DocView.aspx page displays four thumbnails at a time in the thumbnail preview pane.
More Information
You can customize the number of thumbnails to display at one time by modifying the "TheThumbnailDisplay" control.
To customize the number of thumbnails
<WEBLINK:THUMBDISPLAY id="TheThumbDisplay" runat="server">
<WEBLINK:THUMBDISPLAY id="TheThumbDisplay" ThumbCount=x runat="server">
Set x to the number of thumbnails you want displayed in the thumbnail pane.