I think there is a error at the ArrowBocks. In atDiagram I set "useGDIPlus=false". The ArrowBlocks can not be select (with mouse-click or group select) . When I set "useGDIPlus=true" then ArrowBolcks can be select.
It has been fixed and will be available in the next release. If you have urgency to have this fix, please contact us via support webpage (http://www.tmssoftware.com/site/support.asp) so I can send you a patch.