OpenOffice Impress AutoFit (Text Font Auto Resizing)
From my answer to my own question:
Unfortunately, there is currently no global way to disable OpenOffice's stupid "feature" by which it automatically decreases the font size once you've encroached on the text box borders. Even more annoying is the basic fact that for years the developers had held that sort of behavior in Office to be stupid... And then they caved.
In any event, you can only turn this off on a per-presentation basis. In the Master slide, right click on the text box and unselect Edit Style->Text->Fit to frame. That will end this horribleness for the current slide deck.