Splitting the window on large files makes editing horrible

Hi, I love this product, which I've been using for a good long while, and it's only getting better.

However, I have found one slightly annoying problem. When working with rather large text files (database script or huge ASP files), if I use the split screen (top half shows one section of document, bottom shows another) the bottom half can no longer be edited. Pasting text copied from the top half only seems to paste empty space.

Also, if I click on what I'd expect to be a line with nothing on it, the cursor seems to be at the 48th position. But what's actually happening is it's stopping at the postion of the end of line three lines up.

As an experiment, I tried selecting the entire non-existent line (48 characters) copied and pasted them in another window, it pasted the contents of the the above mentionned line, not empty spaces.

Thanks, and still a great product.

Vic