Open a text file with GWD 3.0.
Type some characters. Note they are visible.
Type Ctrl+End to go to the end of the file.
Type some characters. Note they are visible.
From the "Edit" menu select "Word Wrap".
Type some more characters. Note they are invisible.
Move up a couple of lines.
Type some characters. Note that the new characters are invisible, but the characters typed on the previous line suddenly appear.
Alt+Tab to a different application and then Alt+Tab back to GWD.
Note that the previously invisible characters appear.
The Ctrl+End step seems to be the key. If you use 'Page Down', the down arrow or mouse to position yourself at the end of the file the error will not occur. Also, if you position yourself somewhere in the middle of the file instead of at the end the error won't occur.