I do have the same problem. I integrated the paste plugin and I tried
"paste_text_sticky : true" and "paste_text_sticky_default : true". After that I took a look at a lot of other code snippets recommended for TinyMCE version 3.x (in absence of any tips for TinyMCE 4.0b3). But still nothing...
This is what my code looks right now:
"link code preview wordcount paste"
toolbar: "bold bullist numlist link | code preview",
paste_text_sticky : true,
paste_text_sticky_default : true
When I copy some text to the textarea all styles and tags keep remaining.
Any help would be very appreciated.