Ah, dave - I just responded to your tweet, 'cause I saw that first. Thankfully, our forums support answers of more than 140 characters. :-)
It looks like
automatic layout is turned on. (Maybe the template you started your document from did that for you?) If you open up the "Canvas" inspector, unchecking the "
Automatic Layout" box in the "Diagram
Layout" tab will stop that from happening.
The undo issue is something we plan to change in the upcoming 5.0.1 release. There's
a beta build on our site, if you're not averse to running pre-release software.