The Thumbnails panel contains a preview of what is currently on the canvas. This can be a faster way of seeing your layout, instead of using the Run command.
The Thumbnails panel is available when you are using the HTML or Document canvas. The Thumbnails panel is hidden by default. You can display it using the View group, on the Utilities tab.
For more information on customizing panels, see Customizing WebFOCUS App Studio Panels.