The Gmail team has just added a great new functionality to Gmail. Until now, to add attachment to your mails, you had to click "Attach a file", find the good file and click it. Now, you can directly drag the file from your file system to Gmail : Gmail Drag files from file explorer
Gmail Drag files from file explorer result It's a little functionality, but that save a lot of time and that's the kind of feature we (computer scientist) love. Try it, that's awesome !