Fritterandwaste,
I am delighted you find my UDFs useful.
The $iWidth parameter of _ExtMsgBoxSet determines the maximum width of the ExtMsgBox. So you can define any value over the default 370 pixels up to a maximum of @DesktopWidth - 20 and the ExtMsgBox should expand to display strings with spaces up to that width before adding linebreaks. You are correct in thinking that the $iWidth_Abs parameter is to deal with long unbroken strings.
I hope that is clear - if not then please post some examples which do not work as you expect and I will take a look.
M23