check/uncheck threads

mail.css

@@ -565,6 +565,26 @@ div
 	float: left;
 }
 
+.message-list .actions .threads .img
+{
+	display: inline-block;
+	background: url(icons/thread.png) no-repeat;
+	width: 22px;
+	height: 18px;
+	vertical-align: top;
+	margin-top: 4px;
+}
+
+.message-list .actions .threads.checked .img
+{
+	display: inline-block;
+	background: url(icons/thread_selected.png) no-repeat;
+	width: 22px;
+	height: 18px;
+	vertical-align: top;
+	margin-top: 5px;
+}
+
 .message-list .actions .list-sort
 {
 	float: right;

mail.htm

@@ -198,8 +198,8 @@
         <div class="searchbox">
             <input type="text" placeholder="Search mail" />
         </div>
-        <a id="show-dropdown-threads" class="button show-dropdown threads" title="Show Message Thread">
-            <img src="icons/thread.png" />
+        <a id="show-dropdown-threads" onclick="checkDropdown.apply(this)" class="button show-dropdown threads" title="Show Message Thread">
+            <span class="img"></span>
             <span class="down"></span>
         </a>
         <div class="dropdown" id="dropdown-threads">
@@ -474,6 +474,10 @@ function expandChecks()
     this.firstChild.className = e ? 'collapse' : 'expand';
     this.parentNode.nextSibling.nextSibling.style.display = e ? '' : 'none';
 }
+function checkDropdown()
+{
+    this.className = this.className.indexOf(' checked') >= 0 ? this.className.replace(' checked', '') : this.className+' checked';
+}
 function collapseFolders()
 {
     var h = this, e = this;
@@ -508,7 +512,7 @@ function collapseFolders()
     for (var i = 0; i < e.length; i++)
         e[i].addEventListener('click', collapseFolders);
 
-    e = document.getElementsByClassName('message');
+    e = document.querySelectorAll('.message-list .message');
     var selectedMsg;
     for (var i = 0; i < e.length; i++)
     {