By default Dreamweaver’s autocomplete for boolean flags in CFML gives you the option of yes or no, however the coding conventions of the CITS Business Systems Development Web team say that you should use true or false, because this is more consistent with other languages and more readable / understandable.
The autocomplete text Dreamweaver suggests for attributes like <cffunction output="... can be changed with a search and replace on the files in C:\Program Files\Adobe\Adobe Dreamweaver CS4\configuration\TagLibraries\CFML (change the path depending on where you have Dreamweaver installed).
- Find
attriboption value="yes"and replace withattriboption value="true" - Find
attriboption value="no"and replace withattriboption value="false"
Do it for every .vtm file in the folder and boolean attributes will now auto complete properly.
We’ve taken the liberty of doing this for you for Dreamweaver CS4 by attaching a zip file of the updated files. To do this we downloaded GSAR and ran the following two commands (in C:\Program Files\Adobe\Adobe Dreamweaver CS4\configuration\TagLibraries\CFML):
gsar -s"attriboption value=\"yes\"" -r"attriboption value=\"true\"" -i -o *.vtm
gsar -s"attriboption value=\"no\"" -r"attriboption value=\"false\"" -i -o *.vtm

Will this be overwritten every time you upgrade?
Yeah, probably. I’ll look for an existing DW extension to see if something already does this; if not I might have to write one.
In my opinion, you should back-up those Dreamweaver library files before modifying a library file to avoid the problem in the future.