Bug 146796 Error message pop up if display text contain non-digital char when add next item
Description: In decimal type parameter creation,display type is "list box", Error message pop up if "display text" contain non-digital char when add next item. Steps: 1.Create a new decimal parameter 2.Set display type as "list box" 3.Input one item: value:1, display text:test 4.Input another item: Value:2 Actual result: error message pop up: The display text already exists! Expected result: Input item succussfully.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
{
			selectedChoice = (SelectionChoice) ( (IStructuredSelection) valueTable.getSelection( ) ).getFirstElement( );
			if ( selectedChoice == dummyChoice )
			{
				isEnable = false;
			}
		}
		boolean isDefault = isEnable && isDefaultChoice( selectedChoice );
		if ( isDefault )
		{
			changeDefault.setText( BUTTON_LABEL_REMOVE_DEFAULT );
		}
		else
		{
			changeDefault.setText( BUTTON_LABEL_SET_DEFAULT );
		}
		changeDefault.setSelection( isDefault );
		changeDefault.setEnabled( isEnable );
		delete.setEnabled( isEnable );
	}
	private void updateButtons( )
	{
		boolean canFinish = !StringUtil.isBlank( nameEditor.getText( ) );
		if ( canFinish )
		{
			if ( errorMessageLine != null && !errorMessageLine.isDisposed( ) )
			{
				canFinish = ( errorMessageLine.getImage( ) == null );
			}
			if ( columnChooser != null && !isStatic( ) )