Mine

typedef struct
{
        unsigned int row_span;
        unsigned int col_span;
        void *data;
} Ewl_Tree_Data;

Ewl_Tree_Data *my_data[] = {
                {0, 0, "single cell"},
                {0, 1, "colspan cell + 1"},
                {1, 0, "rowspan cell + 1"},
                {2, 2, "coll/row span + 2}
        };

ewl_tree_data_set(EWL_TREE(tree), my_data);