Constraints are working with propagation and seems to work right away as many on a point. Also I fixed a infinite recursive case when a constraint were setup for another constraint a value and the second one setups for the first one. Most probably as Monday (tomorrow) it will be the preview version or Tuesday in the morning. The last four days were really great from stability point of view.
There was also a possible crash that was fixed if you did mirror line against a horizontal line (or vertical line) as the axis extraction was done by scanning internal line structure which differs from the former default line shape (that has two points) and the horizontal/vertical lines (which have only one point). So expect tomorrow to download a preview build with constraints enabled and in the following day (Tuesday) to get a full build with the latest problems found.
Rectangle2p code was removed as Rectangle do not work as of a parallelogram (as worked previously). So wait a bit more for downloading this new release.