Really nice! I've only found two problems: First, many dropdown listboxes use a white background and light grey text color (the text becomes black if i hover the mouse over it, but then I can only read one item at a time). I don't really know why, but the problem seems mainly to crop up in VirtualBox... And the other problem is that in firefox, in the "Create a new bookmark" dialog, the background is a dark grey and the text black. Kind of makes it hard to, for instance, mark tags to use etc.
Not sure it it's any fault of hcalves, though. Might just be some mess-up from the Firefox and VirtualBox teams...
I dont think so. XUL and AIR are unrelated things (XUL is a markup language, Adobe AIR is a framework), and neither are related to making UIs easier to create. XUL is a way to making crossplataforms UIs, so is limited to the underlyings toolkit were it will run. Firefox and OpenOffice are damn slow, buggy and limited for using XUL. AIR applications, although doing cool tricks on the interface, dont follow a single Human Interface Guideline, so each application looks and feel differently. Not good for desktop cosistency.
Gtk is already good enough for most UI tasks. Glade is an UI markup language like XUL, but less limited. Upcoming Clutter, Cairo and Webkit integration enable Gtk apps to have more powerful, custom and OpenGL accelerated widgets. The features are here. The fact is that not all applications make the better use of those.
Well, I remember one of the GNOME devs saying that designing UI in glade is not as easy as it should be.
The thing about Clutter is that we still have to wait until they integrate it with GTK+ so all of the apps could make use of it.
I see nothing wrong in making XUL a native GNOME API. They could write everything from the ground up and force it to use some sort of opengl backend for windows rendering and stuff. Only the file structure would remain the same.
GNOME also needs an animation framework, something like Core Animation in Mac OS X but that's something Clutter is going to be.
The problem is that Glade for long time wasn't integrated into Gtk+ core, but in a libgladexml regarded as an external dependency. That slowed down a lot of features and bug fixes the Glade designer deserved. Only recently they started integrating Glade as a blessed depency. Also, various Gtk+ widgets are clumsy to use (Treeview is one), making harder to design a GUI on Glade than it should be - but then, it's a problem with widgets that suck, not Glade.
Anyway, I don't mind if they adopt XUL or whatever, I just don't see how saying Gnome adopting XUL for the sake of it brings anything new or good. It's slower, it's a huge work, and needs an underlying toolkit to render the widgets anyway.