On Thu, May 14, 2009 at 7:43 PM, Liam R E Quin wrote:
> Go to tool options, choose "corrective mode" and preview "grid".
> Now, align the grid with the item in your picture that you want to
> be horizontal or vertical, and click rotate.
In fact every time you will also need to create a different number of
grid lines so that one of them would be as close as possible to a
potentially horizontal/vertical feature. Straightening with a line the
way Maciej described it would make it much easier.
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