Remove quite a serious Tooltip leak.

Index: frontend/framework/source/class/qx/ui/component/DateChooser.js
===================================================================
--- frontend/framework/source/class/qx/ui/component/DateChooser.js	(revision 8461)
+++ frontend/framework/source/class/qx/ui/component/DateChooser.js	(working copy)
@@ -79,31 +79,39 @@
     var nextMonthBt = new qx.ui.toolbar.Button(null, "widget/datechooser/nextMonth.png");
     var nextYearBt = new qx.ui.toolbar.Button(null, "widget/datechooser/nextYear.png");
 
+    var lastYearToolTip = new qx.ui.popup.ToolTip(this.tr("Last year"));
+    var lastMonthToolTip = new qx.ui.popup.ToolTip(this.tr("Last month"));
+    var nextMonthToolTip = new qx.ui.popup.ToolTip(this.tr("Next month"));
+    var nextYearToolTip = new qx.ui.popup.ToolTip(this.tr("Next year"));
+
     lastYearBt.set(
     {
       show    : 'icon',
-      toolTip : new qx.ui.popup.ToolTip(this.tr("Last year")),
+      toolTip : lastYearToolTip,
       spacing : 0
     });
 
     lastMonthBt.set(
     {
       show    : 'icon',
-      toolTip : new qx.ui.popup.ToolTip(this.tr("Last month"))
+      toolTip : lastMonthToolTip
     });
 
     nextMonthBt.set(
     {
       show    : 'icon',
-      toolTip : new qx.ui.popup.ToolTip(this.tr("Next month"))
+      toolTip : nextMonthToolTip
     });
 
     nextYearBt.set(
     {
       show    : 'icon',
-      toolTip : new qx.ui.popup.ToolTip(this.tr("Next year"))
+      toolTip : nextYearToolTip
     });
 
+    this._toolTipArr = [lastYearToolTip,  lastMonthToolTip,
+                        nextMonthToolTip, nextYearToolTip];
+
     lastYearBt.setAppearance("datechooser-toolbar-button");
     lastMonthBt.setAppearance("datechooser-toolbar-button");
     nextMonthBt.setAppearance("datechooser-toolbar-button");
@@ -637,8 +645,13 @@
       // Create a help date that points to the first of the current month
       var helpDate = new Date(this.getShownYear(), this.getShownMonth(), 1);
 
-      this._monthYearLabel.setText((new qx.util.format.DateFormat(DateChooser.MONTH_YEAR_FORMAT)).format(helpDate));
+      var dateFormat =
+	new qx.util.format.DateFormat(DateChooser.MONTH_YEAR_FORMAT)
 
+      this._monthYearLabel.setText(dateFormat.format(helpDate));
+
+      dateFormat.dispose ();
+
       // Show the day names
       var firstDayOfWeek = helpDate.getDay();
       var firstSundayInMonth = (1 + 7 - firstDayOfWeek) % 7;
@@ -724,5 +737,6 @@
     this._disposeObjectDeep("_weekdayLabelArr", 1);
     this._disposeObjectDeep("_dayLabelArr", 1);
     this._disposeObjectDeep("_weekLabelArr", 1);
+    this._disposeObjectDeep("_toolTipArr", 1);
   }
 });