…from default ‘Points’ to ‘Curves’ or ‘Lines’
Could be spawned by right-clicking on existing automation and then selecting type or with shortcuts.
Could be very handy, i think. And not so complex to develop. 
You haven’t really give any details for people to work with here. What exactly would the tool do?
You can already easily change the curve type by simply using the menu in the Automation editor itself.
I assume you’re talking about some kind of tool which can clean up the recorded points into a simpler curve or something like that?
Have you checked out the existing Automation Cleaner tool?
http://tools.renoise.com/tools/automationcleaner
No, i’m talking about fast way to change type for recorded parameter automation (it is recorded with ‘Points’ by default) in whole song with 2-3 mouse-clicks.
Example: I have 3 minute song. I record continiously changing hither and thither decay of 909s cymbal through whole song. Automation is recorded as Points. Then i have to select each pattern and change type
Automation Cleaner All Patterns will already do it from Points to Curve, although it doesn’t give you the Linear option and it does remove lots of the points and rounds things quite a bit.
A change type for all patterns, without doing anything else, is something I can see as being useful. For the time being you might be surprised how much the Tool dBlue links you to helps.
OK, i’ll try it