Drag and drop items to build a diagram

We are software engineering students that were asked to do a project to help the chemistry department voluntarily outside of classes.

We are trying to build a program to build chemistry labatory diagrams. The main idea would be to have a series of items, being the many components in a labatory (like decanters for example), that could be dragged and dropped onto a canvas. Once on the canvas, they can be deleted, resized or moved. Some of the components are used as link between the other components, have would have to recognize which items are at each end or this connector to validate i开发者_如何学Cf the connection is possible. A little like some UML applications do.

We are only in the conception process at this point, but were wondering how to do something like this. I know Java and C# .net, but never did this kind of projet before. I saw a little of OpenGL with C++, but I only created simple forms on a canvas...

If you have suggestions on functions I have to look at or can point me to some kind of tutorial, it would be greatly appreciated.

---

Regarding advanced GUI features like drag-n-drop, these are very difficult to implement using raw OpenGL ("endless nightmare"). You might look at the answer to this question.