ITreeViewerListener (Eclipse Platform API Specification)

```
public interface ITreeViewerListener
```
A listener which is notified when a tree viewer expands or collapses a node.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`treeCollapsed(TreeExpansionEvent event)`	Notifies that a node in the tree has been collapsed.
`void`	`treeExpanded(TreeExpansionEvent event)`	Notifies that a node in the tree has been expanded.

- Method Detail
  - treeCollapsed
```
void treeCollapsed(TreeExpansionEvent event)
```
    Notifies that a node in the tree has been collapsed.
    
    Parameters:
    
    event - event object describing details
  - treeExpanded
```
void treeExpanded(TreeExpansionEvent event)
```
    Notifies that a node in the tree has been expanded.
    
    Parameters:
    
    event - event object describing details