Currently to we can't add new files (for example: js, css or images files) to static resources.
in order to do this, we have to download, unzip, add the files, zip, reupload and refresh the static resource in TWS.
can we have easier way to do this in TWS? a drag-drop feature will be nice too
ps: the Add new files is currently limited to VF, Apex and either related to this 2