The sidebar in the object page was using up more space than it deserves.
Replace it with a combo box in the subheader. Now that we have more space,
put the CSS node tree and the style properties in the same page again.
Constructing GtkCssStyleChange objects without styles is forbidden, so
don't do it. Instead untangle the callback from the actual update
function and call that untangled function directly.
Instead of having old and new style, now have a GtkCssStyleChange opaque
object that will compute the changes you are interested in for you.
This simplifies change signal handlers quite a bit and avoids lots of
repeated computation in every signal handler.
Showing two lists in a paned was a bit awkward, and space was
getting too limited. Go back to showing just the node list at
first, and make the CSS properties available via a stack. At
the same time, add a right-click context menu to the node list
to make the name and class editing more easily available.
When the CSS style of a node changes, we want to display the new values
in the inspector.
This for example allows to see how styles update on hover or during
animations.
strcasecmp() is unfortunately not universally available, along with
strings.h. Fix the build by replacing strcasecmp() with
g_ascii_strcasecmp(), and remove the strings.h include.
https://bugzilla.gnome.org/show_bug.cgi?id=747604
