The ::drag-leave signal is emitted on the drop site when the cursor
leaves the widget. A typical reason to connect to this signal is to
undo things done in #GtkWidget::drag-motion, e.g. undo highlighting
with gtk_drag_unhighlight().
Likewise, the #GtkWidget::drag-leave signal is also emitted before the
::drag-drop signal, for instance to allow cleaning up of a preview item
created in the #GtkWidget::drag-motion signal handler.
The ::drag-leave signal is emitted on the drop site when the cursor leaves the widget. A typical reason to connect to this signal is to undo things done in #GtkWidget::drag-motion, e.g. undo highlighting with gtk_drag_unhighlight().