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
}
		fElements.add(element);
		if (fTree != null) {
			fTree.add(fParentElement, element);
			fTree.expandToLevel(element, fTreeExpandLevel);
		}
		dialogFieldChanged();
	}
	/**
	* Adds elements at the end of the tree list.
	*/
	public void addElements(List elements) {
		int nElements= elements.size();
		if (nElements > 0) {
			
			ArrayList elementsToAdd= new ArrayList(nElements);
			for (int i= 0; i < nElements; i++) {
				Object elem= elements.get(i);
				if (!fElements.contains(elem)) {
					elementsToAdd.add(elem);
				}
			}
			fElements.addAll(elementsToAdd);
			if (fTree != null) {
				fTree.add(fParentElement, elementsToAdd.toArray());
				for (int i= 0; i < elementsToAdd.size(); i++) {
					fTree.expandToLevel(elementsToAdd.get(i), fTreeExpandLevel);
				}
			}
			dialogFieldChanged();