x11/dnd: Ignore grab broken events from other devices than our DnD device.
The GdkDragContext should only listen to GDK_GRAB_BROKEN events sent to its own pointer device. It turns out that the passive key grabs mistake GDK into sending a GdkEventGrabBroken on the master keyboard, which the DnD machinery mistakes as a signal to cancel the operation. https://bugzilla.gnome.org/show_bug.cgi?id=766442
Showing with 4 additions and 0 deletions