A windowpane is supported in a gasket by a support member so that a space for
allowing
the windowpane to shift therein is ensured between an end surface of the windowpane
and a surface in a channel of the gasket facing the end surface, the gasket having
the channel for receiving a peripheral edge of the windowpane, and the support
member being removable from the gasket. The windowpane can be easily removed from
a body panel by removing the support member and shifting the windowpane into the space.