About the method :
When i test my page locally it works : new tabs are created with the cross buttons which allow to remove them. But when i test my page remotely, on the web server, new tabs are created without the new cross. And it is a graphic issue only because if i click on the right of the tab title it successfully removes the tab. Did you know this graphic issue ?
Unfortunately problem can’t be reconstructed with local samples.
The most probably problem caused by different case of file names on file system and inside the code, please be sure that “close.png” exists in directory used as image directory, and has correct case of name ( all leters lowercase )
If problem still occurs for you - please provide any kind of sample where problem can be reconstructed.