Comment 2 for bug 679971

Hi, yes it would be nice to be able to manage horizontal and control points in the preview, but there are some alternatives that you might not be aware of:

It is possible to add horizontal control points that span different photos, so you can do what you ask in the Control Points tab.

You can straighten manually in the Fast Preview window in 'Drag' mode, drag the panorama so any part of the horizon is in the centre 'crosshairs', then right-click-drag to rotate the panorama until the horizon is level.

Alternatively, if there are vertical features in the scene, drag the panorama so one of them is over the 'crosshairs', right-click-drag to rotate the panorama until this feature is vertical. Then shift-drag the panorama until the second vertical feature is vertical.