The GUI Designer provides a Preview function that enables you to see how the form will look at runtime. When the form runs in Preview mode, you can click buttons, checkboxes, enter text, etc. just as at run time. Of course, there is no functionality at this point.
The Form Preview window enables you to change look and feel of the form, resize it, and exit the preview mode.
To preview a GUI form, do one of the following
Right-click a form, and choose Preview on the context menu.
With the form having the focus, click preview button on the main toolbar.
To exit the preview mode, do one of the following
On the main menu of the Preview Form window, choose Preview | Exit.
Click on the toolbar of the Preview Form window.