Widgets *can* have 4 states: Normal, prelight, selected and active. Not all states are used/supported by all widgets. For example, a label can't get active, it does not make sense. However, when a button gets focus, it's becoming active.
What are you actually trying to do? If you want to get the label that the event was fired for, see
sfg::Context::GetActiveWidget() or use functors.
A side question, how to make window vertically scrollable?
You can't, but you can put everything inside an sfg::ScrolledWindow and add that to the window.
Edit: Oh and by the way, sorry for the download page problems lately. Jenkins CI is going crazy, crashing almost every 15-20 minutes. The download page script fetches live data from Jenkins for the nightly statuses, even when it's down, and that's why it's failing with 500.
The problem will be solved with an updated website and a first binary release, i.e. nightly builds won't be available for quite some time. Instead, we plan to push out smaller releases more often.