RPTools.net

I have two separate questions:

1) Suppose I want to draw a concave U shape with the line tool.
I start with a left-click from one end of the U, making a line down, then right click multiple times making the lower curve, and back up, left-clicking for the final pont.
And the final point gets connected with the starting one, closing the shape and filling it with color. Is there any way to avoid this, other than drawing back a "double border" so that the filling color will keep between the first and second border (or, alternatively, making all separate single lines)?
The border can be made colorless/transparent by selecting the "no color" color for it, but I can't find a way to do it with the filling color, instead.

2) Say I want to draw a horizontal line template.
I click the starting point (a grid intersection), then drag for the direction. But now, if I keep the cursor near the same height of the starting point, the line template gets two squares wide. If I move the cursor higher (or lower), it gets one square wide, but with a "clump" of squares at the end. Since in Pathfinder/D&D (which I'm playing) lines are 99% of the times only one square wide, how do I make a one square wide line template?
Or even wider than two squares, supposing the need may arise.

To draw a U without the fill just right-click the no color (white box with red line).

That's just how the line tool works in MT. I think it fills 2 wide where the line goes through any square. Also, because of rounding(?) some vertices count as a part of the square and some don't. I think it probably could be improved upon. You could use the movement path to show the line you want or just use the line tool in the drawing tools.