Bug 151959 inappropriate screen operation
steps to reproduce: - create a report - add a grid item (3x3) - switch to Outline view - expand the grid item to see its rows and cells - select the grid item, and drag it into any of its own cell expected behavior: - is it an invalid screen operation? if it is, it should be banned actual behavior: - the grid item was disappeared surprisingly
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
}
	/**
	 * Validates the given property value. Validation may map the value onto a
	 * new value that should be used for the actual property update.
	 * <p>
	 * Part of: Property system.
	 * 
	 * @param module
	 *            the module
	 * @param propName
	 *            The name of the property to validate.
	 * @param value
	 *            The value to validate
	 * @return The validated value.
	 * @throws PropertyNameException
	 *             If the property is undefined.
	 * @throws PropertyValueException
	 *             If the value is incorrect.
	 */
	public Object validatePropertyValue( Module module, String propName,
			Object value ) throws PropertyNameException, PropertyValueException
	{
		
		
		ElementPropertyDefn prop = getPropertyDefn( propName );
		if ( prop == null )
			throw new PropertyNameException( this, propName );
		
		try
		{