Bug 201042 [Accessibility]Chart scritp should not add by auto when click the down in keyboard[17]
Description: Chart scritp should not add by auto when click the down in keyboard[0704] Step: 1. New a chart and switch to script view. 2. Let the point on the script function selection. 3. Click the down on keyboard. Actual result: A function will add by auto. Expected result: Customer can not select the function under the second function by keyboard, and it should not be added by auto.
UI/org.eclipse.birt.report.designer.ui.editors.schematic/src/org/eclipse/birt/report/designer/internal/ui/editors/script/JSEditor.java
setEditorText( "" ); 
	}
	/**
	 * Disables the editor UI components
	 */
	private void disableEditor( )
	{
		if ( editorUIEnabled == true )
		{
			getViewer( ).getTextWidget( ).setEnabled( false );
			cmbExpList.setEnabled( false );
			cmbSubFunctions.setEnabled( false );
			butReset.setEnabled( false );
			butValidate.setEnabled( false );
			editorUIEnabled = false;
		}
		setEditorText( NO_EXPRESSION );
	}
	/**
	 * Gets source viewer in the editor
	 * 
	 * @return source viewer
	 */
	public SourceViewer getViewer( )
	{
		return (SourceViewer) scriptEditor.getViewer( );
	}
	/*
	 * (non-Javadoc)
	 *