Saving scripts on partically touchable objects

Is there any way to make an object where some parts are touchable and others are not, which at the same time uses llDetectedLinkNumber() to cut down the number of scripts in the object?

It seems not, since llDetectedLinkNumber() requires there to be a touch_start in the parent prim which then sets the entire object touchable, but I might be missing something?

By 'not touchable' you mean the mouse pointer should change back from the 'touch hand' if it's over the other prims? Because you can always ignore a touch on a prim you're not interested in, so that's a 'not touchable' prim in some sense, but I'm guessing that's not going to work for you.

if you use llDetectedLinkNumber(), you only need one script in the entire linkset

You can always put individual touch scripts in child prims, have no touch scripts in the root prim, and have the children react to being touched by sending link messages to the main script.

I know that, but that means a running script in every touch point.

I'd like to be able to have a single script for dealing with all the touches, without causing the mouse cursor to switch to a hand in locations where it isn't in fact useful to touch the obect.

Total shot in the dark here - and I'm not in-world to test - but maaaaaybeee:

Create a script in every touchable child prim - make sure it calls llPassTouches(TRUE) to pass touches up to the parent - make sure it has a touch event to trigger the hand icon - and then stop the scripts (manually, or through a call to llSetScriptState in each one) to eliminate their lag.

Probably won't work - and even if it does be prepared to for it to stop working at any time - but it would be interesting to know.