DialogComponent 3 questions

Hi,
I have 3 questions about DialogComponent

addDialogComponent(new DialogComponentColumnNameSelection(
                new SettingsModelString(SplitterColNodeModel.COLSEL, ""),
                "Select:",
                0,
                true,
                new ColumnFilter() {
                    public boolean includeColumn(final DataColumnSpec colSpec) {
                        return colSpec.getType().equals(StringCell.TYPE);
                    }
                    public String allFilteredMsg() {
                        return "No columns";
                    }
                }));
        
        setHorizontalPlacement(false);


-When i open the node the item selected into the dropdown menu is the last. Is it possible to select the default index?
-How can i add another option to the menu?
-I need two dialogcomponents on the same line but setHorizontalPlacement doesn't work, how can i resolve it?

Thanks