Problem description: After increasing the font size to a level Impress can't auto-resize the fonts properly if you resize the text-box.

Steps to reproduce:
1. Have a text box
2. Write something into the text-box
3. Increase the font-size so that the text wouldn't fit into the box. Impress will automatically decrease the font size to fit the window. But it decrease it to much. In addition if you decrease the size of the text box, the size of the fonts will be further decreased. In other words the tight connection of font size and text-box size is gone.

Current behavior:
above

Expected behavior:
If auto-resize (Adapt/fit width-height to text) is on, font-size should be adapted to the size of the text-box more closely.

Platform (if different from the browser): 
              
Browser: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:15.0) Gecko/20100101 Firefox/15.0