Sadly, there is no active development happening.
This is really a pity, because until now I could not find any active competitor which would be a good replacement for Echo3.
Did you ever evaluate Vaadin, and if so in what ways is it deficient compared to echo3?
We've been using echo2 for years and its served us well, but its got a few limitations that are hard to overcome.
Yes, i did. And honestly Vaadin is not convincing at all. A huge pile of mess hidden under a clean, shiny box.
For example: Just try to build Vaadin out of the source on your own. I failed a year ago. Nevertheless we do use it, but rather reluctantly.
Echo3 is still superior from a framework point of view to many other Java server-side solutions, but it's not acceptable from a commercial point of view due to the lack of development & support.