Index: trunk/src/org/openstreetmap/josm/gui/layer/gpx/ChooseTrackVisibilityAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/layer/gpx/ChooseTrackVisibilityAction.java	(revision 17320)
+++ trunk/src/org/openstreetmap/josm/gui/layer/gpx/ChooseTrackVisibilityAction.java	(revision 17321)
@@ -326,5 +326,6 @@
             if (c instanceof JComponent) {
                 JComponent jc = (JComponent) c;
-                jc.setToolTipText(String.valueOf(getValueAt(row, col)));
+                Object value = getValueAt(row, col);
+                jc.setToolTipText(col == 2 ? Arrays.toString((Date[]) value) : String.valueOf(value));
                 if (content.length > row
                         && content[row].length > 5