2.5.7:

* Gdk::DragContext: Avoid infinite loop. (Ronald Lembcke)
* Gtk::TargetList: Fix typo toa ctually define this. (Ronald Lembcke).
* Examples now build with the IRIX MipsPro, and AIX compilers.
* Check for the correct atk version in configure.
  (Murray Cumming)
* Documentation:
  - Properties are now documented, using the text from the
    GTK+ documentation.
  - Added MessageDialog documentation.
  - Added CellRendererText::edited() documentation. (Antonio Coralles)
  - examples: book/treeview/editable_cells/:
    Demonstrated data-entry validation.
  (Murray Cumming)
  -