Select this option to show this command in a toolbar button. The image on the button is the bitmap associated with the command.
Note that the image shown on the command handler tab for this command is the icon associated with the command, so you should try to use the same or similar images for both the bitmap and the icon.
Also see:
Does VLF-ONE have a main form menu bar?
Do VLF-ONE and VLF-WIN handle the main form tool bar the same way?
This property is in the Toolbar and Menus tab.