I do not believe that functionality is currently in the editor. I have seen several enhancement request related to code folding/auto code folding. Vote for them and hopefully they will move up the priority list.
This requests the option to select tags to fold as default like CFEclipse does
General Request for Code Folding True/False:
This requests that code you fold stays folded
This requests code folding exactly like DW CS4 (which I have not used, so I don't know what that means)
Go vote for these and hopefully that will help us get these features
Sweet!! Short of it being there and knowing how to turn it on, this is exactly the answer I needed!!