Mirror an action Blender 2.72

Hallo,
In an old version of Blender (2.5 or so) one could insert a mirrored action in the ACTION_EDITOR,
it was next to copy and insert buttons a button to do so.

This third button I cannot see/find in the 2.72 ;-(

Instead maybe this command could be used:
bpy.ops.action.mirror(type=‘CFRA’)

BUT how do I use this command??
bpy.context.area.type = ‘ACTION_EDITOR’

seems to not exist, replacing ACTION by DOPESHEET does not work either

Help is much appreciated
Peter

some pages from the api docs:

area types
context members
bpy.ops.action.mirror

I don’t know what “insert” should mean here.

You can press the ‘+’ button with an action selected to create a copy, press ‘A’ to select all keyframes and afterwards choose Key->Transform->Mirror to flip them.

Thanks, area types API, I had not seen, it confirms no ACTION_EIDOTOR …

It looks like I have to use Key Transform Mirror (tried already but with no succes?)
So this Mirror option I have to analyze what it does and if there are parameters for it …

ok Mirror over Marker (closest (selected?)) mirrors selected … after having added a Marker.
the selected keyframe(s) are mirrored with respect to the marker (if there is only one) to just the other side of the marker where the selcected keyframe(s) is NOT situated, a mirror

But this is not a mirror of what is in an old blender.exe …