First of all I want to thank you and the open source community for providing great open source software for the world to use. I'm been using Linux and open source software for about 4 years now, after I was introduced to computers approx. 6 years ago (I know, where was I?). With guys like you, who contribute to the world with only the cause to provide software, free from a price tag or a copywrite or a lawsuit, people are starting to get it.
Anyway, enough of my nonsense. I've been developing a website for distance runners to use to log their training activity. Where does dia come in? No, I don't want to create a stencil set for the runners and how they might move through the competition during a race (though I commend Alan on his rugby plays--and I think he hit it on the head with mentioning American football plays; Alan, look online for american football play diagrams and you will probably see that the look of it is very intuitive and convertable to rugby. Create a stencil set that handles both American football and rugby simultaneously, and you will become quite popular methinks).
Back to the website. It has roughly 50 database entities and around 100 relationship tables. I've used Dia exclusively to design this database. However, one thing that I noticed in designing it and that caused me to only use the ER stencil set partially is that the Name property of the Relationship stencil is input via a text box and it fixed within the stencil, such that if I input a long name, the stencil grows with the text.
What would be more beneficial for future database designers would be a text area input field for the relationship table and a text segment that is unattached from the stencil--that is, when the text becomes large, it just grows outside the boundary of the relationship stencil. The relationship stencil's size, then would not be dependent upon the text within it.
The reason for the text area is that a user can just insert a newline to continue the text beneath it, thus; he/she is able to have lots of text in the relationship stencil without it going outside the bounds of the stencil by wrapping it. Sure, the wrapping is a little messy, but the stencil size can still be manipulated by clicking and dragging a corner. Futhermore, I definately prefer it to the current stencil, which yields database diagrams with both normal and grossly sized relationships--when it becomes less of a cosmetic issue and more of a diagram readability issue. BTW, because in the current stencil, the diameter of the stencil grows with the text, the area of these stencils can get obnoxiously large with a large relationship table name.
I hope I've explained the feature mod well, and if it makes sense, I hope you guys/girls have time to implement it for future database designers.