Enable attachments drag&drop upload for default skin

skins/default/mail.css

@@ -1448,6 +1448,14 @@ input.from_address
   background-color: #F9F9F9;
 }
 
+#compose-attachments.droptarget.hover
+{
+  background-color: #F0F0EE;
+  box-shadow: 0 0 5px 0 #999;
+  -moz-box-shadow: 0 0 5px 0 #999;
+  -o-box-shadow: 0 0 5px 0 #999;
+}
+
 #compose-attachments ul
 {
   margin: 0px;

skins/default/templates/compose.html

@@ -49,6 +49,7 @@
   <roundcube:button name="uploadmenulink" id="uploadmenulink" type="link" title="addattachment" class="button addgroup" onclick="rcmail_ui.show_popup('uploadmenu', true);return false" content=" " />
 </div>
 </div>
+<roundcube:object name="fileDropArea" id="compose-attachments" />
 
 <script type="text/javascript">
   var composesplitv = new rcube_splitter({id:'composesplitterv', p1: 'compose-attachments', p2: 'compose-container', orientation: 'v', relative: true, start: 175});