Index: src/org/openstreetmap/josm/gui/tagging/TaggingPreset.java
===================================================================
--- src/org/openstreetmap/josm/gui/tagging/TaggingPreset.java	(revision 5356)
+++ src/org/openstreetmap/josm/gui/tagging/TaggingPreset.java	(working copy)
@@ -1254,7 +1254,12 @@
                 if (Math.max(icon.getIconHeight(), icon.getIconWidth()) != 16) {
                     icon = new ImageIcon(icon.getImage().getScaledInstance(16, 16, Image.SCALE_SMOOTH));
                 }
-                putValue(Action.SMALL_ICON, icon);
+                final ImageIcon loadedIcon = icon;
+                GuiHelper.runInEDT(new Runnable() {
+                    public void run() {
+                        putValue(Action.SMALL_ICON, loadedIcon);
+                    }
+                });
             }
         });
     }