To reproduce:

Run Stylepad and select menu item File->Save to bring up a FileDialog.
Place the mouse over one of the text fields in the FileDialog and start typing. Now move the mouse away from the text field and notice that the characters typed no longer go into the text field. Placing the mouse over any text field seems to move the input location to that text field for as long as the mouse is over it. However, it doesn't look like "focus" is going to that field since the caret never begins flashing. The input location should not follow the mouse like this.

Saw this in Solaris 2.8 on an Ultra-1. Could not reproduce on Windows NT 4.