diff --git a/README.md b/README.md
index 9f36ae4da345c602f3b5cbe57a257de701823925..6e676399f45cbaca9aba16e018eb66ecad7f32a5 100644
--- a/README.md
+++ b/README.md
@@ -8,12 +8,18 @@ The rules table contains lines with the following parameters :
 - action : add, modify or delete a header field
 - header field name
 - header field value 
+- comment : a comment 
 - status : on if the modification is active , off otherwise 
 
-We can choose the urls on which the modifications applies by modifying the url pattern.
+We can choose the urls on which the modifications applies by modifying the url pattern. The url pattern must follow the syntaxe define by https://developer.chrome.com/extensions/match_patterns
 
 To save and apply the modification , you need to click on the save button
 
+It's possible to: 
+-  export the configuration in a file (json format)
+-  import the configuration from a file , it support the format of  the Modifyheaders plugin  
+
+
 The extension can be start and stop via the button on the top right.
 
 The code is opensource under Mozilla Public License 2.0 
diff --git a/background.js b/background.js
index f5b552ed5a8826c8ad6f9bca0ad9ea5e8982da92..0be886ffacef3b57d6d5f5b8b37d0bfd1795641c 100644
--- a/background.js
+++ b/background.js
@@ -4,7 +4,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. 
  *
  * @author didierfred@gmail.com
- * @version 0.1
+ * @version 0.2
  */
 
 
@@ -149,7 +149,7 @@ function notify(message)
 function addListener()
 	{
 	var target = config.target_page;
-	if ((target=="*")||(target=="")||(target==" "))target="<all_urls>";
+	if ((target=="*")||(target=="")||(target==" ")) target="<all_urls>";
 	
 	browser.webRequest.onBeforeSendHeaders.addListener(rewriteHeader,
                                           {urls: [target]},
diff --git a/popup/config.html b/popup/config.html
index bd2224cf7905195a809d229b6e00efad8050e525..43c568070022e8c4c74299b95f5f92b4b55afa30 100644
--- a/popup/config.html
+++ b/popup/config.html
@@ -53,7 +53,7 @@ color: #008CBA;
 
 <td width="450">
    
-  Url Pattern* :  <input size="50" id="targetPage"  type="text" value=""></input> 
+  Url Pattern* :  <input size="50" id="targetPage"  type="text" value="">
 </td>
 
 <td width="270" align="right">
diff --git a/popup/config.js b/popup/config.js
index 9d9c60be638fe74052a9f9b57413b792c3df2c67..289824cdb8ca4f8feb5e62c5eb31d38af6100069 100644
--- a/popup/config.js
+++ b/popup/config.js
@@ -5,7 +5,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. 
  *
  * @author didierfred@gmail.com
- * @version 0.1
+ * @version 0.2
  */
 
 
@@ -21,6 +21,7 @@ window.onload = function() {
 	document.getElementById('add_button').addEventListener('click',function (e) {appendLine("add","-","-","","off");});
 	document.getElementById('start_img').addEventListener('click',function (e) {start_modify();});
 	document.getElementById('targetPage').value=config.target_page;
+	document.getElementById('targetPage').addEventListener('keyup',function (e) {checkTargetPageField();});
 	started = localStorage.getItem("started");
 	if (started=="on") document.getElementById("start_img").src = "img/stop.png";	
 } ;
@@ -69,17 +70,24 @@ function create_configuration_data()
 	return JSON.stringify(to_export);
 }
 
+// check if url pattern is valid , if not ,  set the font color to red
+function checkTargetPageField()
+{
+if (isTargetValid(document.getElementById('targetPage').value)) document.getElementById('targetPage').style.color="black";
+else document.getElementById('targetPage').style.color="red";
+}
+
 // check if url pattern is valid
 function isTargetValid(target)
 	{
 		if (target=="") return true;
 		if (target==" ") return true;
 		if (target=="*") return true;
-		return target.match("(http|https):\/\/.[^\*]*\/");
+		return target.match("(http|https|[\*]):\/\/([\*][\.][^\*]*|[^\*]*|[\*])\/");
 	}
 
 
-function save_data () 
+function save_data() 
 	{
 	if (!isTargetValid(document.getElementById('targetPage').value))
 		{
@@ -143,6 +151,8 @@ function readSingleFile(e)
 			// check file format
 			if (config.format_version && config.target_page)
 				{
+				// if url pattern invalid , set to "" 
+				if (!isTargetValid(config.target_page)) config.target_page=""; 
 				// store the conf in the local storage 
 				localStorage.setItem("config",contents);
 				// load the new conf 
diff --git a/screenshot.png b/screenshot.png
index 56ca713532131689a02e23d3a2334e2ee3177597..585c6ddb234dddd8c7cd95568515ef66c06fe1b0 100644
Binary files a/screenshot.png and b/screenshot.png differ