Yeah I've been busy for a while on my work... :(
So... Now I've just updated gtk3 to 3.5.5, then what a horrible appearances had appeared!! It seems to be caused on Unico gtk3 engine, right? For example, weird squared border radius what ignores gtk3 theming. And weird backgrounds behind those texts... OMG. :(
On the other topic, did you guys already see "Midori-gtk3" package? Oh nice thing I wanna accept for that (Yep, we don't need to rebuild that package with "--enable-gtk3" option anymore)!! Even though still midori-gtk3 strongly needed lots of tweaks for "Flash" video playback (remembered well, in past Epiphany was looked like that), But anyway gtk3 theming for web browsing could implement a lot of positive benefits, isn't it? :) Also I don't think gtk3 engine could make huge lack of performance...
Today I really hope that Unico developers could solve such bug ASAP... (Basically, gtk3 3.4.2 or lower didn't get such bug with current unico engine.)
If someone want to employ Mutter Window Manager as "Gnome Classic" session, today we might have to patch for some sources of 3.5.2. Already I've filed this bug to Gnome-bugzilla and devs could solve this issue soooo quickly!! Thanks Jasper!! :-) Anyway those patches would commit to main git branch soon... Now I love Mutter than Compiz clearly because mutter/metacity theming could improve fantastic features like Adwaita, So from a couple of weeks ago, I've applied such theming to my selene. However this implementation leads the lack of awesome appearances on Compiz/Unity session, but I really don't care about it now. I suppose that we (means gtk3 theme creators) might have to improve "Gnome-shell/Mutter" theming at first, and then good to add Unity implementation as 2nd priority, right?
Finally Ambiance, Elementary, Adwaita, and so much other theming seem to get better day by day, so I hope my selene also could get more higher ground... And if Quantal could make a "Gnome3" spin project, I really wanna join it!! :)