You are so long with my suggestion))
There is a lot of interesting features to be implemented (on http://www.softwareideas.net/RequestTracker/Index/2 and much more in my private list of improvements). If it would be possible, I implement all of them immediately, but it needs some time. So I work on new features gradually and add them step by step.
What about dpi bug? and feature of drag and drop + ctrl coping, and also duplicating diagrams by rihgt clicking and making folder system for them.
DPI bug was fixed in version 7.30. Is it not working for you?
Copying using CTRL and drag&drop can be added soon.
Duplication as you want it is kind of versioning, it has larger consequences on whole applicaition and it is quite big feature if I want to implement it properly. SIM is not just a drawing tool it has a model of whole project and its elements on background and it make things (for some features) more complicated as it may seem at first sight.
However I can add (as I mentioned earlier) a Duplicate menu item to the context menu in the project tree, which duplicates a selected diagram (and add it on the same level in the project tree as the original diagram).
I have no oportuinity to check dpi right now. i will let you know when i can.