They are triggered every time you change something in the editor - they are supposed to be triggered only once when the template is then loaded in the actual Lemur on iPAd.
To better understand this, create a project with two interfaces....
Create a onload script that will select the first interface.
on Load
Now go to the second interface and work - script - put objects in it....You will notice the onload script firing up and moving you to the first interface.
If the behavior of an onload script bothers you for further development of a template, simply untick its "checkbox" (in the editor's list window) to work on your template and then just tick it when you are done, before saving your final template.
