When you drag an image from Firefox page in DOpus, the image file is created in your folder.
If you if you press Ctrl V in DOpus while having text in the clipboard, DOpus creates a file containing this text.
If you drag text from Firefox and drop it to a text editor, your text is copied.
But, surprise, if you drag text from Firefox and drop it in DOpus, it's not allowed!
Life would be so much easier if we can create files from text or URLs from Firefox!
Yes? No?
Maybe. 
It seems like a good idea, but we haven't looked into the details of implementing it yet, and we're working through a very long list of other requests and reports.
We read every thread and take in every idea that gets posted, don't worry.