In Autocad when making a dimension when left clicking to place the dimension there is the possibility to drag the dimension to either side of the dimension. This is also possible with Qcad dimension, but it losses the snapping and does not extend the dimension line out to the dimension text.

This is very useful when the two lines the needs a dimension are close together, or overlapping with another.

Attached is two images one for autocad and one for Qcad