You can copy the relevant text and paste it into your new thread, then click the syntax mark to the left of the pasted paragraphs and set the style to be a quote.

Don't forget to add credit to the person who wrote it.

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Or you could just hyperlink to the comment:

Go to the comment you want to quote, right click the time stamp under the name of the person who made it and copy the link. You can then paste it into your new comment and hit return. Providing the quoted comment isn't a mile long it should appear in a box.

A Blend Mode effect is similar to the blend modes used in PS or other bitmap apps to apply effects between their layers, only in this case it's between sheets. If you turn all the polygons mid-grey their shading will create a relatively smooth 'arch' without the fizzy appearance of any texture. You can then blend this to a nice simple rectangular polygon of a roof texture of your choice on an underlying sheet using a Blend Mode set to 100% opacity and Soft Light. Soft Light is a Blend Mode that will shade and highlight the underlying roof texture according to the shade and light of the roof arch.

You are almost there in your thinking towards the end.

Instead of drawing just two slabs how about drawing many strips along the length of the roof, using Shaded Polygon on all of them and then editing the pitch of the resulting strips. It's not as easy as I've just made it sound, but it's achievable. I made an onion dome out of shaded polygons once. You might pick up a few tips on how to do this barrel roof from the blog I wrote about it.

When you open the palette there are two rows at the top that can't be edited. The rest of the palette can be edited just by picking one of them and clicking Define Color.

If you set one of the editable colours as your knockout colour and then edit that colour in the palette at a later date the polygons of that colour will become the new shade, but the colour in the Color Key will remain the same. That means the knockout will no longer work.

That's why the default knockout colour for the Color Key effect is colour number 6 - the magenta in the top row of the palette.

That's another way of doing it I think, and there are many alternatives.

I made an example file using DD3 to show what I described above if you would like to have it.

The water is the background polygon, and the dirt is a polygon on the FLOORS sheet that extends beyond the edge of the map to hide the bevel where it appears on the outside edge as well as the edge of the crevice. If you hide the sheet called SCREEN you will see what I mean about hiding that outer edge.

I added 3 effects to the FLOORS sheet and drew the magenta cut out shape on that sheet. The first two effects were as I described above, and the third was a glow to enhance the illusion of there being a shadow cast on the water below by the edges of the crevice.