This is more of a feature request than a bug report per se, but seeing as this is common functionality in all other airliners and the real 737 to my knowledge, I'm putting it in as a bug report.
In the current version (1.0.4), you cannot select an arrival without also selecting an arrival runway and approach. For countries without runway-specific arrivals (eg. the US), this is quite a pain to deal with. For instance on my current flight from GCN to PSP, PARKS2.PGS DCT EED.CLOWD1, I cannot select the CLOWD1 arrival (which should take me to TRM and then terminate) without also selecting an approach into Palm Springs, even though I may 1) continue on for a visual approach after TRM or 2) not receive approach instructions until I'm closer to the airport itself.