Bug 153523 OK button in parameter dialog is enabled without default value in combo-box
Description: OK button in parameter dialog is enabled without default value in combo-box Steps to reproduce: 1. New a report parameter, combo-box. 2. Click New button, input abc as value, click OK 3. Set abc as default value and close Edit Parameter dialog. 4. New a data source and dataset 5. Edit the parameter, remove abc value and import values from dataset Expected result: OK button is disabled for there is no default value. Actual result: OK button is enabled.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/CascadingParametersDialog.java
value = LABEL_SELECT_DISPLAY_COLUMN;
							}
							else
							{
								value = LABEL_NO_COLUMN_AVAILABLE;
							}
						}
						break;
					}
				}
			}
			if ( value == null )
			{
				value = ""; 
			}
			return value;
		}
		private String getDummyText( Object element )
		{
			String dummyText = ""; 
			int index = getTableIndex( element );
			for ( int i = 0; i < index; i++ )
			{
				dummyText += "    "; 
			}
			return dummyText;
		}
		public void addListener( ILabelProviderListener listener )
		{
		}