8160974: [TESTBUG] Mark more headful tests with @key headful.
Reviewed-by: serb, simonis

8078269: JTabbedPane UI Property TabbedPane.tabAreaBackground no longer works
Reviewed-by: serb, alexsch

8007563: When checking the default behaviour for a scroll tab layout and checking the 'opaque' checkbox, the area behind tabs is not red.
Reviewed-by: alexsch, serb