Actually I did read most of it and the feature you describe is one of the things why I love these players.
@SirReal:
Thank you very much, this is almost it. Compared to they way I was doing it the search will be limited to the current crate as well, which is what I want. 
The only downside is that I cannot filter BPM and Key in this way at the same time. But as the number of songs in my crates is not so high, this will work for me. Especially when I finally get the SC6000s with the bigger display.
Looks like I was thinking too complicated 
Thank you all for taking the time to help me and your kind replies