Separator

This is a horizontal (between menu options) or vertical (between toolbar controls) line separating items/groups of items from each other.

Adding Separator

A new Separator can be created with the help of the add() method of Tree Collection:

toolbar.data.add({
    type:"separator"
});

Separator can have two attributes:

type - (string) the item type, set it to "separator". If not specified - the "navItem" type is applied by default.
id - (string) the ID of a control, automatically generated if you do not set it

You can hide and show Separator with the show()/hide() methods of Toolbar by passing the control's id to them:

toolbar.show(id);
toolbar.hide(id);

Check the full list of available operations in the Toolbar API and Tree Collection API.