tree-view: SIGSEGV after call to `set_drag_dest_row`
gtk_tree_view_enable_model_drag_source have been called, then calling
gtk_tree_view_set_drag_dest_row will lead to a SIGSEGV in the next snapshot.
In particular, the
di at https://gitlab.gnome.org/GNOME/gtk/-/blob/master/gtk/gtktreeview.c#L4845 will be
NULL (there is no
"gtk-tree-view-drag-info" data) so
di->cssnode in the next
switch statement will cause a memory access problem.
I noticed this when I was using
GtkDragGesture for custom reordering of a tree view. I just wanted the insert line to show up on the tree.