CC3 will only open one file at a time, but you should be able to open 2 instances of CC3 - each with it's own file.

You should be able to do this by double clicking the file you want to open.

If it's crashing, maybe try turning Autosave off while you are doing this.

28 minutes :)

I hope so :)

I used to drink gallons of the stuff to stay alert at an office job. Now I'm coffee-total.

Have you got any other city styles you can use?

@Royal Scribe I tried that. It wasn't. Nothing seems to prevent it, or cure it.

By the way, Helen, I'm not saying don't report it to TS - just that the answer may take a bit longer than usual.

Because those bits have been cut out on the water sheet they no longer exist to have properties changed on that sheet. If you want to change what you see through that hole you will need to modify the terrain you can see on the sheets that are revealed by those holes, and not the holes themselves.

What changes to you need to make to the islands?

So the islands are vanishing?

When you change the properties of the water you are also changing the properties of the magenta cut-outs. They need to remain unchanged.

Try starting from the state of your first screen shot and change the ocean again without picking the islands, or carefully deselecting them so they remain unchanged.

Or, if you have already changed everything to the other water fill, try picking the islands only and changing them back to magenta polygons using Change Properties.

That looks complicated.

It has it's limitations since you can't cut a slot out of it, but you're welcome :)

That isn't the template file. It's the example map for the Traveller System Bitmap style.

The template is blank and ready for you to make your own map.

If you want to get started with Cosmographer and what you want isn't in the User Manual there are a couple of recorded live mapping sessions here that might help - even though none of them cover this specific style.