An AVToolButton is a button in the Acrobat viewer's toolbar. Like menu items, the procedure that executes when the button is clicked can be set by a plug-in. Although not required, there generally is a menu item corresponding to each button, allowing users to select a function using either the button or the menu item.

A plug-in can invoke a button as if a user clicked it. Buttons can be enabled (selectable) or disabled (grayed out), and can be marked (selected). Each button also has an icon that appears in the toolbar. AVToolButton objects frequently, but not always, change the active tool (see AVTool). For example, the button that selects the link tool changes the active tool, whereas the button that goes to the last page of a document does not.

Normally, all tools are persistent and remain selected indefinitely. The Option key (Mac OS) or Control key (Windows) can be used to select a tool for one-shot use. Plug-ins should follow this convention to add buttons.

Separators between groups of buttons are themselves buttons, although they are neither selectable nor executable. Because they are buttons, however, they do have names, allowing other buttons to be positioned relative to them.

Plug-ins are encouraged to position their tool buttons relative to separators. Doing this increases the likelihood that tool buttons will be correctly placed if future versions of Acrobat move groups of buttons around.

Acrobat 4.0 and later cleans up separators. It ensures that separators do not appear back-to-back or at the beginning or end of the toolbar. Plug-ins can be liberal with separators in Acrobat 4.0 and later.

You are strongly encouraged to begin your language-independent button names with the plug-in name (separated by a colon) to avoid name collisions when more than one plug-in is present. For example, if your plug-in is named myPlug, it might add a button whose name is myPlug:LastFile. For more information on plug-in naming, see Developing Plug-ins and Applications.