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
* when the delete key is pressed.
	*/
	protected void handleKeyPressed(KeyEvent event) {
		if (event.character == SWT.DEL && event.stateMask == 0) {
			if (fRemoveButtonIndex != -1 && isButtonEnabled(fTree.getSelection(), fRemoveButtonIndex)) {
				managedButtonPressed(fRemoveButtonIndex);
				return;
			}
		}
		fTreeAdapter.keyPressed(this, event);
	}
	
	/*
	* @see DialogField#dialogFieldChanged
	*/
	public void dialogFieldChanged() {
		super.dialogFieldChanged();
		updateButtonState();
	}
	/*
	* Updates the enable state of the all buttons
	*/
	protected void updateButtonState() {
		if (fButtonControls != null) {
			ISelection sel= fTree.getSelection();
			for (int i= 0; i < fButtonControls.length; i++) {
				Button button= fButtonControls[i];
				if (isOkToUse(button)) {
					button.setEnabled(isButtonEnabled(sel, i));
				}