When closing the inspector before the main window, we must take
care to sever all signal connections and weak refs, otherwise
things will go bad when the window is closed later.
gtk_css_section_get_end_position() can return a position one byte beyond
the end of the last line.
gtk_text_buffer_get_iter_at_line_index() accepts only valid
line_number/byte_index pairs. Another solution is to make the
GtkTextBuffer function less strict, by returning a boolean if the exact
position was found.
The CSS parser should also be fixed to always return valid positions.
But it's better to have a safety net in the CSS editor, just in case (a
warning could be print).
https://bugzilla.gnome.org/show_bug.cgi?id=735337
The CSS editor was feeling a little sluggish, because it was
reparsing and reapplying the CSS on every keystroke. Add a small
delay, to make this feel smoother.
The entire UI is constructed with templates, so the wrapper
constructors are never called, except for gtk_inspector_window_new,
which gets called from the GTK+ code.
Moving the inspector into libgtk lets use reuse internals without
having to add public API for everything or inventing awkward private
call conventions.
https://bugzilla.gnome.org/show_bug.cgi?id=730095
