The ability to colour table headers and table groups is great, the next step to make this even better would be to have colour variables so I don’t have to remember the hex codes when editing the DBML (not using the mouse).
Instead of writing Table "http_log" [headercolor: #011B4E] { ... }
it would be nice to be able to name colours, such as:
Colours {
framework #011B4E
security #2D6512
...
}
Table "http_log" [headercolor: framework] {
...
}