Is there an alternative method changing the "actual content-type" (I mean the pulldownmenu with "deactivated", "none",...)? E.g. a normal menubutton?
Properties FORMATLIST will list the content type formats. It's in the default toolbars (under the Folder menu in Opus 11, or the Folder Options menu/icon in Opus 10).
Thanks, don't use the that menu often.
(Piggy backing on here instead of creating a new topic)
Adding Properties FORMATLIST to a button create buttons for each content type. However it also shows buttons for ;-
Reset to folder's format
reset to folder type format
reset to user default format
reset to factory default format
Is there a way to get rid of these buttons?
Ive added Properties FORMATLIST to a button but it show
Making a new one would usually make more sense when the thread is 10 years old. 
Yes, Set FORMATLIST=reset (may also work via the Properties command, but Set is the proper way to do it these days).
Set command docs have more detail.