[Pharo-users] Help with TreeListMorph

Hi, I'm taking a look at the FileDialogWindow: FileDialogWindow new open. On the left, there is a tree. With the halo, I know it is a TreeListMorph. Here is my question: How can I know what is happening when I click on one of the little arrows which are just on the left of a directory name? With my changes, the subtree is very slow to be displayed and I don't understand what is called. Adrien.