On Windows XP, the only way I have found to open 2+ Picture and Fax Viewer windows, is to open one picture in one window, open the print dialog box, then open the subsequent ones. Opening a picture with an already existing Picture and Fax Viewer window, simply replaces this windows picture, with the new one.
So, in order to get the desired functionality, as far as I can tell there are two avenues forward:
1) Alter shimgvw.dll to stop it looking if a window is already open, so that it just opens another (As it does when one window is locked with the print dialog up).
2) Find a way to script asking the user for the first file they want to open, then opening that image, and instructing shimgvw.dll to load the print dialog for that window, then asking about the second file and repeat.
I have attempted to decompile shimgvw.dll, but I am not very good at assembler.
Have also found that this DLL may have a COM interface (http://xpdll.nirsoft.net/shimgvw_dll.html), but not sure what I can invoke by that.
There is also a curious syntax of
rundll32.exe %windir%\shimgvw.dll,ImageView_Fullscreen %1,ImageView_PrintTo /pt "%1" "%2" modified slightly from http://ask-leo.com/comments_003254.php?page=6, but this doesn't seemingly open/do anything despite what I think it looks like it does (Opens %1, then invokes the print dialog from the context of that window)