#2 Very thin line handling issue

[Tronze]

In XLib, a line whose width would be less than 1 pixel at the current zoom level is drawn 1 pixel wide. In Cairo, it is drawn at its true width using anti-aliasing. This means that a line of zero width, which is assigned a colour, does not appear at all under Cairo, but under XLib it is drawn one pixel wide at all zoom levels.

Although Cairo's behaviour gives better quality scaling of high detail images, it is not compatible with most Acorn Draw (.AFF) images. The default line width in Acorn Draw is zero, and Acorn Draw renders this the same way as XLib.

Perhaps there should be an option on a menu somewhere to select how Cairo handles zero-width lines? (Invisible, or 1 pixel wide at all zoom levels)