• improve some widgets (scroll, text) with more key bindings
• focus can be released (only used in text field for now)
• useful widgets for unfoldable area, vlist, and vlist + dynamic filter (e.g. search)

Thanks, I will merge soon.
About the quit handler: Lwd was designed to be exception-safe (if an exception is raised by user functions, the internal state is still consistent). The idea for quitting was rather to simply raise an exception and catch it in the caller of the mainloop.
However I realize that this might not be very future-proof: Lwd might be exception-safe, but user-code might not. It is a bit unsatisfactory to put that burden on all user code just for the purpose of quitting (even though non-local control flow is quite appropriate in this case). Explicit support for quitting might be a good alternative.

(Also, I want to rethink the resource management part : calls to release handlers could be buffered and delegated to the observer; this would better behavior for monadic bind, I will write more about this later)

Merged manually. Thanks.