Using MIME type to open file in different window

Hello, I am popping up a Save File Dialog Box for an Excel file being generated in my system using POI. I am using the MIME type to display this dialog. The problem is that if the user selects 'Open' instead of 'Save', it opens in the same window. Is there any way to set an attribute to tell it to open the file in a new, separate window?

[350 byte] By [Bart69a] at [2007-11-26 15:23:39]