Avoid narrow boxes when using \width as box width unit

Avoid narrow boxes when using \width as box width unit

When the box has a special width, one should not consider that as a fixed width. Otherwise, due to implementation quirks, the width will be set on screen as 1 inch.

A better solution would be to actually set the width by taking in account the contents width, height ans total height. This is not very difficult, but I do not know whether it would workout well in the work area.

Fixes bug #10048.