drools-eclipse/org.drools.eclipse/src/main/java/org/drools/eclipse/editors/rete/RowList.java
public void add(final int depth,
                    final BaseVertex vertex) {
        if ( this.rows.size() < (depth + 1) ) {
            final int addRows = depth - this.rows.size() + 1;

            for ( int i = 0; i < addRows; ++i ) {
                this.rows.add( new Row( (depth - addRows) + i ) );
            }
        }

        ((Row) this.rows.get( depth )).add( vertex );
    }
public void add(final int depth,
                    final BaseVertex vertex) {
        if ( this.rows.size() < (depth + 1) ) {
            final int addRows = depth - this.rows.size() + 1;

            for ( int i = 0; i < addRows; ++i ) {
                this.rows.add( new Row( (depth - addRows) + i ) );
            }
        }

        ((Row) this.rows.get( depth )).add( vertex );
    }
Adds new vertex to specified depth

@param depth depth for vertex
@param vertex vertex