Imagine a button to preview a HTML file in the system's default browser.
I would prefer a WebKit sheet in the same window as the document that I can toggle with a keyboard shortcut.
Opening in a browser means the file has to be saved somewhere and it opened in the browser. I then have to clean up manually. At the very least I have to close the browser tab. This sucks for rapid iteration where I make many changes and preview them in succession. Making 20 edits and having each of those sitting in browser tabs is tedious.
Customer support service by UserEcho