CL_GUI_ALV_GRID, PRINT_TOP_OF_PAGE How to print content of 1. row of page

I use CL_GUI_ALV_GRID with method set_table_for_first_display and implemented an event handler with handle_top_of_page.

Does anybody know how to write something dependend on the contend of the first row on each page as headline in the event PRINT_TOP_OF_PAGE?

For example: Page1 Row1 Matnr=5 I want to write: 'Five' as heading of page1. Page2 Row1 Matnr=21 I want to write 'twentyone'. The problem is, that I don't have access to the data, that will be printed in the first row on each page and I can't calculte somthing like a cursor position because there can be several rows of subtotals and units.

I'm a little bit desperate and start to beleave that there is no way to access the data of the first row.

If somebody has an working idea, this would be a breakthrough and help me a lot.

Hope to hear something from the experts.

Guenter