Add onClick feature

README.md

@@ -25,6 +25,7 @@ All functions read JSON formatted parameters
       "group": "groupname",
       // style and icon-style are optional
       // item can have text and/or icon
+      // item can have click action "signal" or "delete"
       "items": [
           {
 	      "name":"",
@@ -32,6 +33,7 @@ All functions read JSON formatted parameters
               "style":"",
               "icon-style":"",
 	      "icon":"",
+	      "on-click":"",
           }, ...
       ]
       }
@@ -48,6 +50,15 @@ All functions read JSON formatted parameters
   }
 
 
+When text/icon is clicked and on-click parameter is set to "signal", 
+extension emit one of the following signals :
+
+  * onClick
+  * onRightClick
+  * onDblClick
+  * onRightDblClick
+
+
 Example
 -------