I have several Top Bar Hives in Somerset and Dorset, UK, semi-cylindrical in shape with the entrance at the sunny end. The bees tend to propolise the entrance during the wasp season but not elsewhen. They do, however, propolise any gaps between the bars throughout the year. If I want a crop of propolis I remove one bar and spread the others slightly to take up the space. On my next visit I can remove a matchbox or two of propolis with my hive tool.
So it seems that they don't desire top ventilation.
Chris
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