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
if ( paramHandle == newParameter )
			{
				if ( columnIndex == 0 )
				{
					value = LABEL_CREATE_NEW_PARAMETER;
				}
				else if ( columnIndex == 1 )
				{
					if ( !isSingle( ) || paramHandle == getFirstParameter( ) )
					{
						value = LABEL_SELECT_DATA_SET;
					}
				}
				else if ( columnIndex == 2 )
				{
					if ( isSingle( ) && paramHandle != getFirstParameter( ) )
					{
						value = LABEL_SELECT_VALUE_COLUMN;
					}
				}
			}
			else
			{
				switch ( columnIndex )
				{
					case 0 :
					{
						if ( paramHandle != newParameter )
						{
							String paramName;