Hello Mohamed,
thanks a lot for your immediate reply!
As for the kerning bug, it’s an issue we already know: kerning of alternates are not correctly rendered in LivePreviews. We have no satisfying solution for now
OMG 
The nasties bugs are those which can’t be found!
At least, the resulting font file works properly!
Unfortunately I can’t code.
I’d be happy to help!
What I was wondering since the early days:
Why are there two separate areas for adjusting and for preview?
I would think (greenly) one single are for both purposes would do the job properly.
OK, at the moment, the adjusting area is working fairly lame.
I once copied several lines into it.
It felt like the app had crashed 
The good news is that we’re wroking on kerning groups and kerning import…
Stay tuned. We’ll send you a Beta version if you’re interested.
I’m as tuned as possible 
Being eager for this function and asking for it since ages
I’d be happy to receive a beta ASAP!
Good luck on bug-hunting! 
All the best!
Hybi