Scrolling over VNC

I have a couple of Piduino setups now where I program my Arduino with the IDE using my Raspberry Pi to program and log my Arduino. I access my Pi's over WiFi/VNC where the connection is pretty good, and everything works fine except the Arduino IDE, which quite frequently throws a wobbly and won't scroll the text nicely.

Here's the scenario - I press the down arrow till the cursor gets to the bottom of the screen, then each line of text should move up as I keep pressing 'down'. What actually happens is that the bottom line of text is updated, but the other lines above are not. Then if I press Page-Up followed by Page-Down it sorts out and I can read it again.

Anyone else get this..? Any ideas..?

lsm99you