From http://glade.gnome.org with some corrections:
Dual Project Formats
Now projects can be edited in libglade format and in GtkBuilder format, offering you a load of new features only available in GtkBuilder format (also removing access to deprecated widgets).
Projects can be converted, the operation is undoable, and can result in data loss when some objects/widgets can't be ported to the target format (classic libglade format projects can always be converted to GtkBuilder format).
Target Project Version
Glade now lets you target your GTK+ version for your project, giving you visual feedback and warnings about objects, properties and signals that you may be using that are not available in the targeted version of GTK+.
Interestingly Glade 3.6 depends on GTK+ 2.14, but gives you access to GTK+ properties from GTK+ 2.16 even if only running against 2.14.
Access to new objects
In GtkBuilder format, we have access to a whole new world of objects we've never seen before in Glade:
* GtkAction: Represent your UI frontend widget(s) by an Action. Actions are a great abstraction for UI components and let you have multiple screen widgets that correspond to a single "action" all of which conform to said action's state. * GTK+ MVC Framework: Now we give you access to GtkTreeView, GtkIconView, GtkComboBox (as a view), GtkListStore, GtkTreeStore in Glade. That pretty much says it all. I encourage you all to try it, define columns and data for your treemodel, define columns and renderers for your treeview, in an all in one treeview editor. * GtkIconFactory: Add your own stock id definitions using an icon factory, define graphics for different widget sizes and widget states. * GtkSizeGroup: Add widgets to logical groups that ensure all members have the same size.
Sexy New Editors
With a new internal interface, we allow plugins to define editor layouts on a class level basis. We now have customized editors for GtkButton, GtkImage, GtkLabel, GtkEntry and many more (and they all have sized to fit word wrapping property description texts in them).
The Python Plugin
This is finally worked out into a plugin; its been around for a while now but wasn't publicly/stably released to my knowledge. What it does is allow Glade to introspect and load your python classes properties and signals and add it to the palette automatically (with the use of a one or 2 liner user catalog). Documentation coming, or ask Juan Pablo ;-)
* Inspector lets you filter and search the project with an added entry (behaves like DevHelp's search entry but on the project). * You can edit widgets inline with their editor in a dialog (Edit Separately in context menu). This editor window will stay on the same widget when selection changes).