can't use it

Flickr has changed their buttons with flat ones instead of the thick-bordered ones they had before. I didn’t like the new ones very much because they lack the affordance of being “pushable”:

Here’s a crude version on how I’d make them more button-y

Also, I think UI-wise the buttons could lead the user to do the more desirable action for Flickr. In this case, they have placed a Preview button so users would read what they write and end up leaving smarter comments :) Why not highlight it a bit?

or then in the style that Facebook has introduced:

It’s good to provide users guidance in the form of defaults actions in forms and dialogs. A good example is Mac OS UI’s dialogs such as: