When a plug is embedded in a socket, we need to also plug the at-spi
tree, so that screen readers can find the at-spi content of the plugged
widgets.
This change does this plugging automatically: on the plug widget, an
additional _XEMBED_AT_SPI_PATH property is set to provide the at-spi path
(just like we have _XEMBED_INFO for other X11 information), and when
embedding it, the socket reads it, and makes it as its only child.
Since GtkPlugAccessible can not inherit both from AtkPlug (a child of
AtkObject) and from GtkContainerAccessible (a child of AtkObject), we
actually make GtkPlugAccessible a child of an AtkPlug, and that's what
will be embedded (in at-spi terms) into an AtkSocket.
Similarly, GtkSocketAccessible can not inherit both from AtkSocket and
GtkContainerAccessible, so we make it a parent of the AtkSocket that
embeds the AtkPlug.
This change depends on atk 2.35.1 which implements the at-spi technical
details.
This separates out atk-bridge-2.0 dependency, which is not part of atk,
but of at-spi2-atk.
And let GtkPopover use it as its GtkAccessible implementation, this
accessible sets the POPUP_FOR relationship to the relative-to widget,
and keeps track of changes there.
https://bugzilla.gnome.org/show_bug.cgi?id=725864
The button now claims its menu as a child for a11y purposes,
which makes it possible for ATs to see it when the navigate
the tree top-down.
Update the a11y test to match.
GtkFlowBox is a container that its children in a reflowing
grid, which can be oriented horizontally or vertically.
It is similar to GtkListBox in that the children can
be sorted and filtered, and by requiring a dedicated child
widget type, GtkFlowBoxChild. It is similar to GtkTreeView
in that is supports a full set of selection modes, including
rubberband selection.
This is the culmination of work that has happened in the
egg-list-box module, and earlier in libegg. The origins of
this code are the EggSpreadTable in libegg, which was written
by Tristan van Berkom. It was moved to egg-list-box and
renamed EggFlowBox by Jon McCann, and I gave it some finishing
touched in the flowbox-improvements branch of that module.
We add a separate gtk-a11y.h single-include header for
them. This header will work much the same as gtkx.h. It
will be installed in /usr/include/gtk-3.0/gtk, but you
have to include it separately.
