Hi Petr.
Firstly, WELL DONE on this program.
As a suggestion:
It would be great to have a low tone alarm on reaching a given distance from the Altitude bug.
This would work the same way as air spaces currently work, but only with a different tone.
The ability to change the distance from the bug ,say, 100ft or 200ft etc would be really great.
In any case your program gets a 5 star rating from me without any doubt.
Keep I mind that you have a lot of people out there that appreciate your work.....Most often silently.
Cheers.