| 摘要 |
The described technology is directed towards a pre-child user interface element in a user interface tree that draws before the parent element draws, (and thus before any conventional child element of the parent draws). For example, based upon current state data such as whether the parent element has focus, the pre-child may draw a highlight or the like before (so as to be beneath) drawing the representation of the parent element, to indicate the focused state (or and/or other current state or states). The user interface tree maintains a property that it is composable because the parent user interface element code is independent of what any of its pre-child element or pre-children elements do when invoked. |
