overlap property

The number of pixels from where the pixels corresponding to the scrollOffset will be painted up to the first pixel that has not yet been painted on by an earlier sliver, in the axisDirection.

For example, if the previous sliver had a SliverGeometry.paintExtent of 100.0 pixels but a SliverGeometry.layoutExtent of only 50.0 pixels, then the overlap of this sliver will be 50.0.

This is typically ignored unless the sliver is itself going to be pinned or floating and wants to avoid doing so under the previous sliver.