> I would like to be able to drag a button,
What kind of button? From where?
> assign the select
> clearTurtleTrails and set the target to the World by using only
> mouse and interaction
>
> I saw that I can change the selector, arguments....but not the
> target Is it possible? Do am I missing it?
Three ways I can think of:
1. Using a world script button:
* open a viewer on the world (via a halo click).
* go to the "pen trails" vocabulary
* drag out the phrase "world clear pen trails".
* drop it in the World. It becomes a script.
* from the script's menu, choose "hand me a button".
2. Using a scripted button:
* drag out a button from the "Supplies" flap.
* hit the "show script" halo button (pale green plain button at lower
right".
* insert "world clear pen trails" phrase from the World's viewer as
above.
3. Make a button from the menu. This is what I do.
* open the World menu.
* Bring up its halo.
* bring up the halo on the "restore display (r)" item.
* drag the green "duplicate" or the black "grab" handles.
* drop on the World.
--
Ned Konz

Oh, I forgot two more ways, neither of which will work for you <g>:
1. You can open a properties sheet on your button (halo, properties; 
maybe need to use shift depending on your Preference)
Then go to the "button" tab. There's an area where you can drop a 
phrase tile. However, it doesn't seem to work right (at least it 
didn't for me), and it doesn't accept a regular tile morph (which 
would be needed for the World).

2. And yet another:
SimpleButtonMorph and its subclasses actually have a "set target" menu 
choice. See SimpleButtonMorph>>addCustomMenuItems:hand. But I've 
forgotten how it was supposed to work, and maybe we've broken it 
somehow. The idea was that you'd look at the position of the event 
that popped up the menu, and then if that was over a Morph (but not 
the World), the menu would offer to let you set the target to that 
Morph.