Hi Misha,
Sorry this response took a while - I meant to reply earlier but the mail got lost.
Here's my opinion on the matter:
It's a hard decision to make. Adding functionality can be good but you also want to keep your software simple. In this case, it's up for the developers/designers of Transmission to decide which one of these provides more value to their users. They should consider their target audience and what they would want: do they value the added power over the expense of increased complexity?
I do think it's very good that you've taken notice of this change though... The difference between one and two mouse clicks will not sound shocking on its own, but these changes can quickly add up. Transmission is known for its simplicity and I personally think that's very valuable. I can only tell them to be careful, but I'm sure the developers know this. :)
By the way, the submenus inside the drop-downs shouldn't be there according to the HIG [1]. On the other hand. the HIG is about guidelines, not rules, and Transmission isn't part of GNOME. Again, it's up to the developers to decide if the tradeoff is worth it.
What I *would* do however is give the default selection in the drop-down list a better label. In your screenshot they both say "All 3", which doesn't make clear what they do. Maybe something like "All torrents", "All states" or "All trackers" would be clearer here? Just an idea.
Jef
[1]
http://library.gnome.org/devel/hig-book/stable/controls-option-menus.html.en