showScrollbarV property
Overridable getter to indicate that the scrollbar should be visible, even when a scroll is not underway.
Subclasses can override this getter to make its value depend on an inherited theme.
Defaults to false when RawScrollbar.thumbVisibility is null.
Implementation
@override
bool get showScrollbarV =>
thumbVisibility ??
_scrollbarTheme.thumbVisibility?.resolve(_statesV) ??
false;