I think the WE implementation is an acceptable, but the keyboard shortcuts really need to be changeable. As it stands, this extension removes the ability to select text properly inside web forms, pages, or any other browser UI text fields. Alt+Arrow keys allow you to jump the cursor through text one word at a time, and Shift + Alt + Arrow keys is how you can select one word at a time.

With these commonly used navigation elements overridden, the browser becomes unusable for anything more involved than clicking on things. Doing development in Firefox is definitely no longer possible, which is ironic given that Tile Tabs has generally been one of my most useful dev tools ...

Edit : interestingly this behavior seems to be a little different in FF than in other browsers I've used it in. Some text fields retain the ability to navigate the cursor, so my initial review was a bit hasty. One particular area I use this feature though is with selected text on a page itself. Say I've loaded an admin UI and I want to grab some chunk of text that appears in the middle of a larger block...I can mouse over where I want to start selecting text and click once. This will place an invisible cursor of sorts, where I can then use the Shift + Arrow keys or the Shift + Alt + Arrow keys to set the marked text for copy.

This is especially useful when the text you want to select is a link, but you don't want to actually click the link for whatever reason.