Having a single click open the Collection as a Contact Sheet is a bug. It is completely unusable. The next build won't have this problem. You'll either need to double-click to open or right-click and choose to open from the contextual menu.
-Kirk
I mentioned earlier in this thread that having to click on a collection (thus opening a contact sheet) in order to add images was a pain, but that was before “Add selected items here” was added/fixed. With that now working, if I’m browsing a contact sheet and I want to drop photos into various collections, I select some images, right-click on any collection (regardless of whether it is currently selected or not) and choose “Add selected items here”. This is brilliant, as it means there is no longer any need to click on a collection first, which means I'm no longer unnecessarily opening contact sheets every time I want to add photos to a different collection. So with that fixed and working beautifully, I can't understand what the problem is with single-clicking on a collection to open it. As I say it WAS a problem, but not any more, and in fact the only issue I see now is the inconsistency of behaviour between tabs.
The way I see it, having to double-click a collection breaks some very fundamental PM behaviour. Whether you click a folder while in Favourites or you click on a keyword in the Filter tab or click on something in the Browse tab, it's always a single click to opens a contact sheet. But now the behaviour is different only in the Collections tab. In my view, having different clicks do different things depending on the what tab you're in just complicates the user experience.
Maybe I'm missing something, but the only reason I can think of for the current behaviour is if you add to a collection by right-clicking images and selecting “Add to collection”. In that case the collection needs to be selected first, and selecting a collection without bringing up a contact sheet every time is helpful. Firstly though, I honestly can’t see why anyone would use “Add to collection” now that “Add selected items here” is working. It does exactly the same thing but it saves you the step of having to select a collection first. Secondly, if for some reason you still want to use “Add to collection”, maybe an Option-Click or Control-Click or something on the collection could select it without opening a contact sheet. That way the single-click behaviour could remain consistent throughout PM.