In the Java runtime, mixins are reported to be abstract, where as in Javascript they are not:

@Js
mixin MyMixin { }

...

echo(Env.cur.runtime)
echo("MyMixin.isMixin    - ${MyMixin#.isMixin}")
echo("MyMixin.isAbstract - ${MyMixin#.isAbstract}")

Gives:

java
MyMixin.isMixin    - true
MyMixin.isAbstract - true

js
MyMixin.isMixin    - true
MyMixin.isAbstract - false

Ticket promoted to #2455 and assigned to andy

Also note that mixins aren't reported as const in Javascript either:

@Js
const mixin MyMixin { }

...

echo(Env.cur.runtime)
echo("MyMixin.isMixin    - ${MyMixin#.isMixin}")
echo("MyMixin.isConst    - ${MyMixin#.isConst}")

Gives:

java
MyMixin.isMixin    - true
MyMixin.isConst    - true

js
MyMixin.isMixin    - true
MyMixin.isConst    - false

Ticket resolved in 1.0.68

Fixed - probably a few bugs fixed by this for anyone introspecting mixin types