Dear Stefan,
I am an enthusiastic beginner in chess and it made me extraordinary happy to find your really usefull chess software. Congratulations!
I have one suggestion, which maybe other people suggested before, but I did not check the forum history. Sorry in advance if I am the 20th who suggests the following suggestion.
It would be nice if instead of the position tree there would be a position graph. With the help of a graph it would be easy to see where different lines join and opening A transforms into opening B. Currently joined lines are shown in the tree as redundant subtrees.
Best Regards,
Zoltán Vajda