Bug 27491 Cannot add classpath variable to project
build id : 200212020010 The buttons OK and extend... are always disabled in the add variable dialog
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/dialogfields/ListDialogField.java
public ColumnsDescription(ColumnLayoutData[] columns, String[] headers, boolean drawLines) {
			this.columns= columns;
			this.headers= headers;
			this.drawLines= drawLines;
		}
		
		public ColumnsDescription(String[] headers, boolean drawLines) {
			this(createColumnWeightData(headers.length), headers, drawLines);
		}
		
		public ColumnsDescription(int nColumns, boolean drawLines) {
			this(createColumnWeightData(nColumns), null, drawLines);
		}
		
		private static ColumnLayoutData[] createColumnWeightData(int nColumns) {
			ColumnLayoutData[] data= new ColumnLayoutData[nColumns];
			for (int i= 0; i < nColumns; i++) {
				data[i]= new ColumnWeightData(1);
			}			
			return data;
		}
	}
	
	protected TableViewer fTable;
	protected ILabelProvider fLabelProvider;
	protected ListViewerAdapter fListViewerAdapter;
	protected List fElements;
	protected ViewerSorter fViewerSorter;
	protected String[] fButtonLabels;
	private Button[] fButtonControls;