[shotwell] map: only stop map movements on drag when map is unlocked

[Jens Georg <jensgeorg src gnome org>]

commit fcd388b35754c380a3d3dd63ee31ba78b7897a81
Author: Andreas Brauchli <a brauchli elementarea net>
Date:   Sat Jul 2 10:21:56 2016 +0200

    map: only stop map movements on drag when map is unlocked
    
    Also signal when a drop will not be accepted (due to map edit lock)

 src/MapWidget.vala | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/src/MapWidget.vala b/src/MapWidget.vala
index bb6159ed..899c9475 100644
--- a/src/MapWidget.vala
+++ b/src/MapWidget.vala
@@ -296,7 +296,10 @@ private class MapWidget : Gtk.Bin {
     }
 
     public override bool drag_motion(Gdk.DragContext context, int x, int y, uint time) {
-        map_view.stop_go_to();
+        if (!map_edit_lock)
+            map_view.stop_go_to();
+        else
+            Gdk.drag_status(context, 0, time);
         return true;
     }