one way to fixed sliver app bar overlap

```dart

// find sliverlist renderobject
RenderSliver? renderSliver = context.findAncestorRenderObjectOfType();

// determineStuckOffset
double determineStuckOffset() {
double dy;

try {
dy = localToGlobal(Offset(0, -renderSliver.constraints.overlap), ancestor: renderSliver).dy;
} catch (e) {
// ignore and fall-through and return 0.0
dy = 0.0;
}
return dy;
}

```