Dialog closeText option documentation very vague on effect

The closeText option of the dialog widget is described this way:

Specifies the text for the close button.

What text "the text for the close button" refers to is non-trivial. I realized the dialog had a close button, but as it just shows a black cross (like a native window), I thought that text had to be somewhere else. After asking on #jquery, paul_irish revealed that the text is the label for the X button - but that text usually doesn't show because CSS hides it

Something is wrong - either the text should show or the description should clarify what text is refers to.