And another thing about Mary Marvel...
According to what I can piece together from interviews, the whole Darkening-of-Mary-Marvel thing was an idea that Grant Morrison had for Final Crisis. She was always going to be possessed by one of the evil New Gods as they ushered in the Fifth World. If "New Gods" and "Fifth World" make your eyes glaze over, don't worry. They do mine too. But that's not important.
Where I'm going with this is that DC - wanting to build excitement for Final Crisis - decided to tell the story of Mary's possession in their weekly Countdown to Final Crisis series. Only they apparently neglected to talk to Morrison at all about his plans, because in Countdown Mary's not possessed by an evil being, but is "seduced" to darkness by a combination of Eclipso, Darkseid, and Black Adam's powers. And the reason she's got Black Adam's powers is because hers mysteriously disappeared and she couldn't bear to be without any.
And where I'm going with that is that this wasn't the first time Mary had lost her powers. Only before, she handled it a lot better.
That's right. The real Mary Marvel didn't go begging for new powers from any supervillain who'd give them to her, she put on a costume and decided to go crime-fighting anyway. The Fortress Keeper has the whole story.