It seems only the player who has drawn a card from the deck can flip it over. I’m not sure whether that’s how Vassal handles cards normally, or a problem of the specific module. Only once the card gets flipped by whoever has drawn it, the option becomes available to everyone.
Is there a way to make everyone able to flip cards, regardless of who draws them?
Uh, ok, I’ve managed to figure it out on my own. That’s funny how I tried everything but the “any of the specific sides” option 
Still, it’s a shame the editor requires specifying sides manually every time, rather than just let one pick from all the sides in the module. Fixing my module will be rather tedious 
That’s why using prototypes is a good design practice for module
building.
If a prototype had been used, you would only need to modify the
prototype that is part of every card.
Messages mailing list
Messages@forums.vassalengine.org
forums.vassalengine.org/mailman/ … engine.org
Post generated using Mail2Forum (mail2forum.com)
Oh, I rely on prototypes a lot. I still had to fix quite a lot of those, however, due to a large number of different types of cards across the module and its various extensions. I don’t suppose this could have been done more efficiently - it’s all about different back designs, so a single masking prototype wouldn’t do.
Fortunately, I’ve managed to skip some work by editing buildFile directly and copy-pasting sides. I’m always working blindly with that, though, and I’m never 100% sure what I’m doing.