Try to change the video mode with video_set. I have had blurred text when I run my application 800x600 window mode, but when I set the resolution from 800x600 -> 1024x768 and back to 800x600 in window mode, the text became readable again. Don't know if this is the correct way though.

Would like to ask why recommending to turn of anti-aliasing on the graphic card, when this blurred text problem occurs? Thought it was a nice feature for games in general and A7 to get rid of jagged edges.