Bug 136571 Drop property is displayed in Property Editor for all kinds of cells.
Description: Drop property displayed in Property Editor for all kinds of cells. Drop property is only supported by cells in group but it is listed in every kinds of cells even in grid cell which will mislead users.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/SimpleGroupElementHandle.java
{
			Object next = iter.next( );
			if ( !( next instanceof DesignElementHandle ) )
				return false;
			if ( ( (DesignElementHandle) next ).getExtends( ) == null )
				return false;
		}
		
		return true;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.GroupElementHandle#isPropertyReadOnly(java.lang.String)
	 */
	protected boolean isPropertyReadOnly( String propName )
	{
		for ( int i = 0; i < elements.size( ); i++ )
		{
			PropertyHandle propertyHandle = ( (DesignElementHandle) elements
					.get( i ) ).getPropertyHandle( propName );
			
			
			if ( propertyHandle != null && propertyHandle.isReadOnly( )
					|| propertyHandle == null )
				return true;
		}
		
		
		return isInvalidInMasterPage( propName );