Then I add % system 'c:\Program Files\Adobe\Reader 8.0\Reader\AcroRd32.exe', 'D:\www\my.pdf'; in HTML file and load in browser.
You are doing this in your Mason file, right? This will run Acrobat on your server, not the client's machine.
++ for the trick with iframe - it works. How to use it when I return 'application/pdf' in HTTP header?
You have to create a URL which returns your PDF file. You then specify that URL as the src= parameter to the iframe. For instance, try this in the above example HTML document: 
<iframe src="http://www.niso.org/publications/rp/RP-6-2008.pdf"></ifra
+me>

[download]

In reply to Re^3: Open generated PDF in new tab/new page in HTML::Mason by pc88mxer
in thread Open generated PDF in new tab/new page in HTML::Mason by grizzley

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