Change screenmode

Hmm that's strange Squatting Neville's example works perfectly. But in a real program it doesn't - my program works for one change only before getting the blank rectangles instead of text - and not at all without the code I mentioned.

Perhaps an alpha problem?

Screenshot1 is how should look. www.elliottproductions.co.uk/temp/screenshot1.jpg

Screenshot2 is how it looks after 2 changes of graphics mode. www.elliottproductions.co.uk/temp/screenshot2.jpg