Index: /trunk/src/org/openstreetmap/josm/gui/layer/geoimage/ImageViewerDialog.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/layer/geoimage/ImageViewerDialog.java	(revision 18923)
+++ /trunk/src/org/openstreetmap/josm/gui/layer/geoimage/ImageViewerDialog.java	(revision 18924)
@@ -189,4 +189,11 @@
             }
         });
+    }
+
+    @Override
+    public void hideNotify() {
+        super.hideNotify();
+        this.currentEntry = null;
+        this.imgDisplay.setImage(null);
     }