tooltips added on Gantt chart to view the details of the issues

(added csshover behaviour to make it work under IE)

git-svn-id: http://redmine.rubyforge.org/svn/trunk@160 e93f8b46-1217-0410-a6f0-8f06a7374b81

public/stylesheets/application.css

@@ -548,7 +548,6 @@ font-size: 1em;
   height:8px;
   font-size:0.8em;
   color:#888;
-  background:#aaa;
   padding:0;
   margin:0;
   line-height:0.8em;
@@ -558,6 +557,22 @@ font-size: 1em;
 .task_done { background:#66f url(../images/task_done.png); border: 1px solid #66f; }  
 .task_todo { background:#aaa url(../images/task_todo.png); border: 1px solid #aaa; }
 
+/***** Tooltips ******/
+.tooltip{position:absolute;z-index:24;}
+.tooltip:hover{z-index:25;color:#000;}
+.tooltip span.tip{display: none}
+
+div.tooltip:hover span.tip{
+display:block;
+position:absolute;
+top:12px; left:20px; width:270px;
+border:1px solid #555;
+background-color:#fff;
+padding: 4px;
+font-size: 0.8em;
+color:#505050;
+}
+
 /***** CSS FORM ******/
 .tabular p{
 margin: 0;