Paul,
Those drum-based toploaders are quite common and popular in France in particular. They usually have a taller deeper drum that isn't as wide so they can fit a similar amount of clothes as a standard front loader but take up less floor space. They're ideal in a small apartment.
There are usually two doors in the drum that can only be opened by pushing them inwards. So, during the spin / wash the doors can't be pushed open by clothes at the inside of the drum.
There's a second door on top that seals the tank
