Way to CANCEL uploads

If i drop a large file in the chat window and it starts uploading, there is no way to stop the process. If i uploaded the wrong one or just dont want to transfer it after seeing how slow it is, i should be able to simly cancel it. I shouldn't have to wait until the upload is complete before being able to undo it.

If i am missing something, please let me know. I couldn't click on the progress bar or right click on it either so i see no way to do this. Oversight maybe?