Many of the UI elements that were previously dialogs are now shown as pop-overs with no obvious close mechanism. The expected close method is for the user to click anywhere outside the pop-over. For pop-over's based on a selection, e.g. Get InFo, do not click on the source selection, but rather anywhere else outside the pop-over.
A pop-over can also be closed using the Escape key (⎋) but, depending on the task at hand, this may also revert the last edit on the pop-over so use with caution—unless that is the intent!