When DnD is started from an X11 client, mutter now sets up an special
grab that 1) Ensures the drag source keeps receiving events, and 2)
Moves an internal X Window over wayland clients as soon as the pointer
enters over these.
That window will act as the X-side peer for the currently focused
wayland client, and will transform XdndEnter/Position/Leave/Drop
messages into wayland actions. If DnD happens between X11 clients,
the window will be moved away and unmapped, to let these operate as
usual.
https://bugzilla.gnome.org/show_bug.cgi?id=738312
X11 client windows now hook a X11-specific MetaWaylandDragDestFuncs
that converts these into Xdnd* messages, and an additional selection
bridge has been added to take care of XdndSelection, and the data
transfers done through it.
https://bugzilla.gnome.org/show_bug.cgi?id=738312
This piece of code hooks in both wl_data_device and the relevant X
selection events, an X11 Window is set up so it can act as the clipboard
owner when any wayland client owns the selection, reacting to
SelectionRequest events, and returning the data from the wayland client
FD to any X11 requestor through X properties.
In the opposite direction, SelectionNotify messages are received,
which results in the property contents being converted then written
into the wayland requestor's FD.
This code also takes care of the handling incremental transfers through
the INCR property type, reading/writing data chunk by chunk.
https://bugzilla.gnome.org/show_bug.cgi?id=738312
