This happens in 2014.03 but did not happen in 2013.09.
When you zoom by mouse interaction, the Zoom action of the DisplayIteractor is called. It checks if the movement was along the 'zoom direction' (that can be 'updown' or 'leftright'), and calculates the distance of movement. If the movement is orthogonal to the zoom direction, the distance will be zero.
The scale factor is calculated based on the distance, in this case it will be 1.0, i.e. no zooming.
However, the mitk::DisplayGeometry::ZoomWithFixedWorldCoordinates is called in this case as well. This would not be a problem, if it would not change the scale factor and the origin, but unfortunately only the scale factor remains constant, the origin is changed, and the modification event is sent.
As a result, if you listen to the DisplayGeometry modification events, you will interpret the change as panning the image instead of moving.