Hard-code width of calendar popup to 600px and fix ellipsis for events

We might want the width to be expressed in em or in % of the available
monitor width. Or perhaps a combination of all three. I don't know.

Signed-off-by: David Zeuthen <davidz@redhat.com>

js/ui/dateMenu.js

@@ -65,7 +65,7 @@ DateMenuButton.prototype = {
         this._clock = new St.Label();
         this.actor.set_child(this._clock);
 
-        hbox = new St.BoxLayout();
+        hbox = new St.BoxLayout({name: 'calendarArea'});
         this.menu.addActor(hbox);
 
         // Fill up the first column