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
}
	/**
	 * Checks whether a type of elements can reside in the given slot of the
	 * current element. Besides the type check, it also checks the cardinality
	 * of this slot.
	 * 
	 * @param slotId
	 *            the slot id of the current element
	 * @param defn
	 *            the element definition
	 * 
	 * @return <code>true</code> if elements with the definition
	 *         <code>defn</code> can reside in the given slot. Otherwise
	 *         <code>false</code>.
	 */
	private boolean canContainInRom( int slotId, IElementDefn defn )
	{
		if ( slotId < 0 || slotId >= getDefn( ).getSlotCount( ) )
			return false;
		ISlotDefn slotDefn = getDefn( ).getSlot( slotId );
		assert slotDefn != null;
		if ( !slotDefn.canContain( defn ) )
			return false;
		
		
		
		String name = defn.getName( );
		if ( ReportDesignConstants.TEMPLATE_DATA_SET.equals( name )
				|| ReportDesignConstants.TEMPLATE_REPORT_ITEM.equals( name )
				|| ReportDesignConstants.TEMPLATE_ELEMENT.equals( name ) )