Hi,
Even if this is not pure UML, since it can be done quite easily, so here a first beta that support this:
https://dl.dropbox.com/u/13064071/plantuml.jar
@startuml
class Foo1 #red ##00FFFF {
}
class FooDashed ##[dashed]blue {
}
class FooDotted ##[dotted]blue {
}
class FooBold ##[bold] {
}
@enduml
As you can see, you can specify after ## a color for the line, or a style (dotted/dashed/bold).
This is a first draft, with probably some bugs.
For consistency, we should probably also add a skinparam, and also skinned stereotypes.
We are also thinking about allowing foo1 <|<|-- foo2 to draw double arrow inheritance arrrows.
Feedback appreciate, and thanks for your suggestion!