title: How to restart page number from 1 in different group of BIRT report
body: <p>Backgroud:
  Use Java + BIRT to generate report.
  Generate report in viewer and allow user to choose to export it to different format (pdf, xls, word...).</p>
  
  <p>All program are in "Layout", no program in "Master Page".
  Have 1 "Data Set". The fields in "Layout" refer to this DS.
  There is Group in "Layout", gropu by one field.
  In "Group Header", I create one cell to use as page number. "Page : MyPageNumber".
  "MyPageNumber" is a field I define which would +1 in Group Header.</p>
  
  <p>Problem:
  When I use 1st method to generate report, "MyPageNumber" could not show correctly. Because group header only load one time for each group. It would always show 1.</p>
  
  <p>Question:
  As I know there is "restart page number in group" in Crystal report. How to restart page in BIRT?
  I want to show data of different group in 1 report file, and the page number start from 1 for each group.</p>