The middle mouse button can be used to edit segmentation curves in the `Review' window and manifold definitions in the `Reslice' window. The user traces out an edit curve with the middle mouse button. The edit curve replaces a portion of the old curve as follows.
In the `Reslice' window, for defining the manifold shape, if the edit curve intersects the old curve more than once, then the old curve is replaced with the edit curve between the first and last points of intersection. Bits of edit curve outside the intersections are irrelevant. If the edit curve intersects the old curve only once, then the longer bit of the edit curve is spliced on to whichever bit of the old curve it joins most smoothly, replacing the other bit of the old curve.
In the `Review' window, for editing segmentation contours, the edit curve must intersect the old curve at least twice. Only the first and last intersections count. One of the sub-curves of the old curve between the intersections will be replaced by the edit curve. Which sub-curve is replaced is determined as follows. If both joins between the curves can be made smooth by replacing one particular sub-curve, then this will be the sub-curve that gets replaced. If the intersection angles conflict, so that one has to be acute, then the shorter sub-curve will be replaced.
If Stradx replaces the wrong portion of curve in either the `Reslice' or `Review' windows, simply click once with the middle mouse button to toggle the replaced section.