riched20a with ES_READONLY - can still change formatting ?

Hello all,

Programming related :

I've got a simple dialog on which I placed a riched20a control which I have 
given, among others, the ES_READONLY style.  The result is that I cannot 
edit the text itself.  Which is what I was after.

However, I was rather surprised to discover that some shortcut-keys 
affecting text-formatting (ctrl-R, ctrl-L and likely more) still work. :-(

Question : How do I make the text *really* read-only ? *inclusive* 
text-formatting.

Is that possible at all ?   Which style would I need to add/remove / which 
GWL_* bit would I need to set/clear (I've not seen anything in that regard) 
?

Remark: I need to be able to select-and-copy text from it though. Using the 
mouse or keyboard.

Regards,
Rudy Wieser