[gtk+] (27 commits) Non-fast-forward update to branch wip/cosimoc/viewport-gadget

[Cosimo Cecchi <cosimoc src gnome org>]

The branch 'wip/cosimoc/viewport-gadget' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  6239d65... viewport: use gtk_container_class_handle_border_width()
  1c44a33... viewport: trivial code cleanup
  cb07104... viewport: port to use a gadget

Commits added to the branch:

  81da0b8... Adwaita: fix notebook close button (*)
  9f06474... Updated Czech translation (*)
  9290aa7... GdkSeat: Use g_intern_static_string() for signal names (*)
  b3c1454... Add docs for GtkCssSection (*)
  158dbbc... Use CSS syntax for drop highlighting (*)
  c998fae... Add deprecation warnings for pseudo states (*)
  39b4efb... Adwaita: Don't use deprecated pseudo classes (*)
  b3dbf3f... Drop the :dnd syntax altogether (*)
  26d8688... Redo the CSS docs (*)
  79b6d48... gtkframe: remove unused variable (*)
  5404e12... gtkframe: format fix (*)
  1f154f5... Fix a surface leak (*)
  f669ccc... docs: Add missing value syntax for border-image (*)
  787f600... inspector: Remove some dead code (*)
  80a9172... inspector: Don't leak weak references (*)
  8bfbb2c... Cosmetic change (*)
  c4ca671... test-css-parser: Add a way to generate output (*)
  f3069d7... css: Redo the pseudo class deprecation warnings (*)
  ab18212... Fix the pseudo-classes-known css test (*)
  2b27096... Fix outline-radius css parser test (*)
  eb09bee... css: Deprecate :sorted pseudo class (*)
  e8ba058... checkbutton: Update state initially (*)
  ba1636b... statusicon: Avoid criticals (*)
  8fc58cf... viewport: use gtk_container_class_handle_border_width() (*)
  ec1503a... viewport: trivial code cleanup (*)
  2104583... viewport: port to use a gadget (*)
  8f3e0c3... viewport: don't render a background over the bin window (*)

(*) This commit already existed in another branch; no separate mail sent