Click the menu icon to enable this plugin.

After the plugin is enabled, select the required orthogonal projection view tab. Then click an hold on a control point of the row of the surface to be rotated.

Drag the mouse to rotate the row of control points. Note that the control points rotate around the control point in the first column of the row. Note also that the angle of rotation changes as the mouse is dragged relative to the view origin. The angle is displayed in the mode text box above the 3D view.

This plugin is "accumulative". This means that you can incrementally enable rows of control points for rotation while the plugin is enabled.

Release the mouse to complete the rotation.

Click the menu item to disable the plugin mode.