In theory this is possible with a jQuery block and POST to the /contents service. See the previous example I left you regarding putting a JS into an HTML Widget's managed files.
Hope that helps.
I used J-Meter and Badboy to detect and record the "Create" and "Save" actions. But the request was redirected several times. The software could not replay the "Create" and "Save" actions after record them. Parameters also lost. Any solution that I can detect the request and imitate it?