Bug 54737 Libraries dialog doesn't remember status of items in library tree
Preferences > Java > Build Path > User Libraries: The dialog does not seem to correctly remember the status of the items in the "Defined user libraries" tree. When I leave the dialog I close (un-cascade) all items. When I open the dialog again, most of the items are open (cascaded) again. This is disturbing because I cannot overview the items. It's like opening the Windows explorer with not only the drives shown but all folders being open.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/dialogfields/TreeListDialogField.java
public TreeViewer getTreeViewer() {
		return fTree;
	}
	/*
	* Subclasses may override to specify a different style.
	*/
	protected int getTreeStyle() {
		int style= SWT.BORDER | SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL;
		return style;
	}
	protected TreeViewer createTreeViewer(Composite parent) {
		Tree tree= new Tree(parent, getTreeStyle());
		return new TreeViewer(tree);
	}
	protected Button createButton(Composite parent, String label, SelectionListener listener) {
		Button button= new Button(parent, SWT.PUSH);
		button.setText(label);
		button.addSelectionListener(listener);
		GridData gd= new GridData();
		gd.horizontalAlignment= GridData.FILL;
		gd.grabExcessHorizontalSpace= true;
		gd.verticalAlignment= GridData.BEGINNING;
		gd.heightHint= SWTUtil.getButtonHeightHint(button);
		gd.widthHint= SWTUtil.getButtonWidthHint(button);
		button.setLayoutData(gd);
		return button;
	}
	private Label createSeparator(Composite parent) {
		Label separator= new Label(parent, SWT.NONE);
		separator.setVisible(false);