what was the name of the rooftop on 1969 buick electra

Are you talking about interior? If so Electra interiors were trimmed in fabric. Electra 225s were trimmed in Calais cloth or leather trim, except for convertibles which were trimmed in vinyl. An optional Custom interior featured leather trim, while another featured vinyl with contrasting vertical stripes and front bucket seats with a storage consolex and power two-way seat adjustment.

six-window pillarless configuration was the actual roof top design I believe. If that's what you are asking.