[gtk] (5 commits) Non-fast-forward update to branch wip/exalm/headerbar-dragging

[Alexander Mikhaylenko <alexm src gnome org>]

The branch 'wip/exalm/headerbar-dragging' 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:

  b440532... window: Make gtk_window_update_toplevel() non-static
  0390369... Add GtkWindowHandle
  dda9211... headerbar: Use GtkCenterBox internally
  4e0ea3e... headerbar: Include GtkWindowHandle
  5e90b8b... window: Stop handling dragging and titlebar actions
  7cbe003... testsuite: Update bloomfilter test

Commits added to the branch:

  8bd44cb... Add GtkWindowHandle
  4135276... headerbar: Use GtkCenterBox internally
  8ca1e0d... headerbar: Include GtkWindowHandle
  f453883... window: Stop handling dragging and titlebar actions
  8d24711... testsuite: Update bloomfilter test