Lately, I've seen the widget below appear in GTK applications. I can't find it in Glade. What is it?
Looking at the Totem code, it looks like a set of GktButtons inside a GtkToolbar, with a CSS style applied and using symbolic icons (which are also installed by the theme in Ubuntu) instead of the stock ones.
Here's an example in Python
More info on GTK+ 3 CSS styles: