Earlier today I changed a setting for how ads are displayed in HM3. In a word, it was broken before -- ads weren't clickable in most of the major browsers. So I changed the stacking order of the app and the ad and now the ads actually function. Hooray! Before they were just annoying without actually generating revenue but now they do both!
Unfortunately that introduced several problems, one of which was the cancel button on the Save dialog box was obscured by the ad. That's been fixed now (you might have to clear your browser cache).
The other major problem is that the ads also show on the full-screen preview. I don't know how to fix that but I'll start working on it tomorrow.