Function foreground 

pub fn foreground(child: impl IntoUiNode, foreground: impl IntoUiNode) -> UiNode

P Custom foreground fill. Allows using any other UI node as a foreground overlay.

The foreground is not interactive and not hit-testable. The foreground is layout to fill the widget, it does not affect the size of the widget. It is rendered over the widget child and background, it is rendered under borders by default.

Note that nodes can only exist in a single place in the UI tree at a time, so if you set this property in a style the foreground node will only appear in the last widget that uses the style, the foreground_fn property does not have this issue.