UXToolbarItem

UXToolbarItem is one entry of a UXToolbar. It holds its type (a clickable item, a fixed space, a flexible space, or a separator), the ident a native backend maps to platform icon art, the label, your tag, and its natural width. The toolbar’s layout writes the laid-out x, w and visible fields; visible is false when the item moved into the overflow.

The add* methods create items. The laid-out fields are public because the layout results are public, and the overflow tests read these fields.