Wolfgang Schuster wrote:
> but he want to "collect" the figures on one page and not
> every on a new page.

That's part of the issue, but not the entire issue.  Attached is the equivalent LaTeX source and the resultant PDF (both gzipped due to ridiculously low 40k email limit).  LaTeX appears to float a series of figures placed with the "htbp" as follows:

1) Try to float the figures on the current page.  They can be "here", or at the top or bottom of the page.
2) If the figures weren't placed on the current page, finish out the current page with content (see pdf page 1), unlike ConTeXt's "force" option.  Start a new page containing only floats and keep doing so until all floats are flushed.  (pages 2-4 of the PDF)
3) Try to place content on what would be the last float page (see page 5 of the PDF).

The closest analog that I can see in ConTeXt is the "force" placement option for floats, which is mean to ensure strict ordering.  The main difference is that the LaTeX "htbp" placement option will fill the remaining vertical whitespace with content before starting a float page.

Cheers,
Mike