lacks an icon (error I suppose (stop sign), but perhaps exclamation?)
lacks a good error message
I realize that the error message is pretty self-explanatory, but it could have been a bit more of a sentence, i.e., "The disk is full." or "The target disk is full" or "The copy or rename/move operation can't continue as the target disk has become full." or something along those lines. I realize that that would perhaps require some additional changes to the code and additional translations would be needed, so perhaps this should be seen as a request for improvement in the future, but the icon can easily be added without additional code or translation.