I am synchronizing the vertical scroll events of two RichTextBox controls using the EM_SETSCROLLPOS/EM_GETSCROLLPOS method. While things seem to be working well for short text files, I am hitting the 16-bit limit with long text files. Specifically, when I have text over 65,535 pixel lines, the message handler appears to be scaling the scroll position values and scroll positions of the two controls are getting out of sync. As a last resort, it may be possible to determine the scaling factor each time and apply some correction code before passing the scroll positions, most likely with a significant performance hit. My question is, is there any way to work around this 16-bit limitation? If not, are there any third party controls to do the same?