Hmm … I still have trouble with third party plugins and tinymce. I'm sorry, if I ask very noobish questions …
I now installed a plugin called jbimages in my custom folder site/tinymce/plugins and activated it for my textfield. The upload button appears in the editor, but when I hit it, the text in the appearing popup contains source code (I don't understand) and upload doesn't work. (See screenshot).
The same plugin worked fine, when it was in wire/modules/Inputfield/InputfieldTinyMCE/tinymce-3.5.8/plugins.
Any help woud be very appreciated. Thanks in advance, tron1000