https://bugzilla.gnome.org/show_bug.cgi?id=691990

Replace use of gtk_style_context_set_background() in the _realize() vfunc
with use of gtk_render_background() in the _draw() vfunc. This is based
on the _draw() implementations in similar GTK+ containers such as GtkGrid.

Instead, simply use a GtkImage.

https://bugzilla.gnome.org/show_bug.cgi?id=744194

Found by Coverity Scan (while scanning Glom).

https://bugzilla.gnome.org/show_bug.cgi?id=686470

action_sensitive_cb can be called with the dnd tool item when it doesn't
have an ancestor.

Bug #661240

Bug #661240

Bug #661240

  o Removed egg_spread_table_dnd_steal_events() api
  o Added apis:
     egg_spread_table_dnd_set/get_drag_enabled()
     egg_spread_table_dnd_set/get_drop_enabled()
    The set/get_drag_enabled() apis use an EggDragEnableMode enumeration
    to decide whether dragging:
      - Is completely OFF
      - Is enabled (dragging starts when and where children dont handle events)
      - Overrides events on top of child widgets
  o Changed signature of 'widget-drop-possible' signal for something more
    useful (added out 'drop_possible' parameter in addition to boolean
    handled return value).
  o Added documentation

Without this we will crash if you're running a broadway app from
inside a X11 session.

Do not use deprecated autoconf macros
Use new libtool syntax
Use silent rules if available

Now that EggSpreadTableDnd uses event boxes internally as
intermediate children for all added child widgets it's no longer
needed to try to manually handle drag'n'drop for no-window widgets.

This implicitly fixes a bug in the manual handling of drag'n'drop
as well as removes a bunch of unneeded code.

Adjusted test case to add some corner case widgets to test (and use the new EggSpreadTableDnd apis).

This commit makes the EggSpreadTableDnd own event boxes internally
for all added children and adds some new apis:

  - egg_spread_table_dnd_insert_child/remove_child()
    Custom api to add/remove children since normal container apis are
    reserved for internal use by the spread table.

  - egg_spread_table_set/get_steal_events()
    An added 'steal-events' property controls whether the spread-table
    should trap all pointer events over the added children (temporally
    allows drag'n'drop of widgets that also handle events).

This patch uses the dragged widget itself to draw an icon for Drag'n'Drop.
Currently there are still problems if the widget itself is not 100% viewable.

If the 'window-dragging' property of GtkToolbar is set (as it is in adwaita)
then the Toolbar starts the drag of the window on 'button-press' event.
We prevent this by connecting a handler for 'button-press' which prevents
the handler of the toolbar to be run while in edit mode.

Fixes bug #647265

These happen while compiling as C++.

Whatever this once did, it does not do it anymore and is unmaintained.

Maybe it was once an old hack to do transparent windows.

I noticed this only while compiling it as C++.

 o Implement ->leave_notify() vfunc to unset the currently pressed
   button and avoid false drags that may follow in some corner cases
 o Added "drag-end" signal callback to drag source to cancel the drag
   properly when the event happens too fast (sometimes drag-begin/drag-end
   are called and no drag-leave/drag-drop or drag-failed are envoked).
 o Simplified the code a little bit by adding the animate_out_drop_target()
   function.

The "child-accepts-drop" control was not working (only the parent control was).

Because it was moved to GTK+ as GtkTreeModelFilter long ago.

However, this still won't build because it tries to use a custom
GtkFileSytem.