Hey,
The Lazarus Docu says in
http://wiki.freepascal.org/Anchor_DockingConstraints: The DockMaster clears the maximum Constraints and will restore them on undock.
For my program i need minimal sizes for the dockable windows, also when they are locked. I was able to somehow achieve the constraint behavior by extending a lot of the TAnchor* classes from the unit AnchorDocking. But I guess it would be better to implement a proper handling of constraints in the framework. I wonder whether other developers have the need for constraints?