Comment 5 for bug 171797

vlad seghete wrote
> is there a way to rotate a drawing such that a given line
> becomes horizontal (without knowing the angle of the line)?

If you didn't mean to rotate the canvas itself, but only objects or (parts of) the drawing content: Inkscape 0.49 will support rotational snapping so that you can drag-rotate a selection and let the end node of a line snap to e.g. a horizontal guide, or align it with the grid (see bug #170919).

(depending on your platform, you can download & test a recent development snapshot build which already has this feature).