Originally posted by kUROBix
Or that sign it's a texture by itself, not a repeating one, like the wall it's on.
It doesn't look square because it has transparent pixels, but it works just like every other texture.
To make a texture like that sign, you have to draw a square face and put it very near the wall but not on it
. Just place it at a distance of about 3cm from the wall.
After you have applied the texture to that face right click on it and do texture > position.
Drag the red pin to the bottom left corner of the face (be sure it snap to the vertex), then drag the green pin to the bottom right corner.
This way there are better chances your texture will hold its position when exporting with the plugin.