You probably have attach enabled (button lower right)

Was the original polygon properly closed? In CC3+, it isn't a polygon unless it is a closed shape (it's then a path), and if you try to set a fill style for a path, it is only applied to the line itself (And keep in mind, in a CAD based software like CC3+, being closed is a property of the entity, not just that it looks closed on visual inspection, there is a close path command by right clicking the explode button).

Your map is nice, but I would recommend you look a bit at your grass, the repetition of the texture is a bit much. This can often be fixed by adding more stuff to the map, combining it with other grass/terrain textures, or changing the resolution of it so it doesn't repeat quite as much. Also, maybe not use the same floor style for all the rooms. You can also use a shaded polygon to angle the fill in that stand-alone building to fit the direction of the building.

Since CC3+ always tries to open the last map on load, there is a chance that something has gone wrong with it.

First, to open CC3+, try to either double-click on another .fcw file on your drive, since that will open CC3+ with that file instead of your map, or rename your map file before starting CC3+, since this will cause CC3+ to not find it and will open up without a map (showing a black screen).

After that, you can try opening your map using File -> Open. If that crashes CC3+ immediately we know where the problem lies and can take it from there.

In that case, I think it is best that you put in a tech support request. You'll find the form on your registered user pages. They should be able to get you back up and running.

The lines have a fixed length. They are then scaled based on the width of the drawing, so if that doesn't match the ratio, they don't end up being long enough, or alternatively, too long. The new map wizard doesn't distort images, it always scales them proportionally. ()

The maps from the Poncegraf Fief have now been added to the atlas. Thanks for the contribution @Quenten .

The vegetation for DD3 is found on the Skirmish button (the last one).

The problem you are encountering here is that there is both an outline and a landmass. When you use change properties, you end up changing both of them (or all 3 in this case). You need to select just the land poly.

In your case, the easiest way to do that is when using schange properties to select the landmass by the edge of the inner lake, instead of the outer coastline. There should only be one entity there. This saves you from doing other tricks to select only the right entity.

Looking at your screenshots, it looks like the white gap is part of the image. CC3+ doesn't add or remove anything from the image (shouldn't anyway, and I've been unable to get it to). So my recommendation is to have a closer look at the source image, seems there is a border on the bottom and right sides.

There is a setting called 'outlined' on the settings for the fill in the fill dialog, you can check that it is disabled, but I don't think that's what you are seeing here.

While that symbol is a raster symbol, it is really just some simple geometric shapes. You should be able to easily enough draw that yourself using the circle and polygon tools in CC3+ and define it as a vector symbol. The user manual goes through symbol creation on page 75 if you're unsure of that part.