I have a need to create graphics editor to run under Windows. The graphic symbols will look somewhat like UML class symbols. One must be able to enter a name and then text elements in each of several parts of the symbol, and they must resize themselves for the amount of text.
I'm looking for source code where this is already implemented.

Failing this is there a package (eg OpenGL) with which this can easily be done - where one defines a multi-line symbol and then has the software draw instances of it.

I would really not like to implement the whole editor from scratch so some other suggestions would be welcome.