Instaviz author here. This is actually intentional, Instaviz is really optimized for quickly sketching out ideas and thoughts and not having to worry about layout. I'm planning a 2.0 version which will allow some reorganization of the nodes within a layout.
Kudos to you for figuring out shape recognition. It took me a long while to get my head around it.
Thanks pixelglow for taking a look at the Lekh Diagram.
For me, writing the shape recognizer did not take much time. But designing/thinking the overall app usability took much more time.
It looks like your shape recognition is handled differently from Instaviz. Yours is more oriented toward general purpose drawing, whereas Instaviz is more tuned toward recognizing specific shapes.
Yes, the Lekh Diagram first recognizes a general shape which is matching to user's drawing then uses various heuristics to convert it to regular shapes like rectangle, parallelogram etc.
There is setting that switches of most of second step (regularizing shapes). In the Misc->Settings, there is "regularize shape" switch
The sketch recognition might be patented (at a minimum there is previous art), and I know it is only one piece. But that is enough to create some unwelcome letters. And it is also the reason why I am against patents. This is a case where copyright is enough, and IP would be counter-productive
And regarding the instaviz, this very restrictive. It does not allow you to rearrange the shape the way you want.