Unveiling a tree folder

Hi everyone,


Another beginner problem : I want to select a given cross in a folder tree like the select_line.png image.

The register function gave me the correct syntax to do this through a script, but the definition of the object is a problem : it is refered to thanks to its Index, like shown in the Object repository (cf plus_description.png)

problem is, if another cross is checked for example, the position of the one I want changes, and the index doesn't correspond anymore. Is there an absolute way to target this cross ?

Thanks a lot !