No and yes. You cannot run a second instance from within a macro directly. But you can configure a user tool at
Advanced - Tool Configuration which starts a new instance of UltraEdit. Then you can run this tool with the macro command RunTool.
But you must take into consideration, that the macro environment waits until the executed tool has terminated. That would lock your first instance until you close the second instance. A workaround for this problem is to use the Windows START command as I have posted at forum topic "
Opening a Tool with a macro and switching back to UE?".
But why do you need a macro to open the second instance just for viewing files without anything you don't need in view mode only?
You can create a copy of your uedit32.ini in the same directory, but with a different name and run uedit32.exe with the parameter
/i="full path and name of alternate INI file". Then you make the necessary changes ONCE and that's it. Whenever you call now UltraEdit with this alternate INI customized for viewing files it will look as you have it specified the first time (bars, menus, window position, etc.).
Please note: If you have NOT enabled
Configuration - Application Layout - Miscellaneous - Allow multiple instances the method with the alternate INI will not work well with an UltraEdit version prior 13.10. Since UE v13.10 there is the command line parameter
/fni (force new instance) which will allow you to open a second instance of UltraEdit with the alternate INI independent of the configuration setting for multiple instances.
For more about command line parameters of UltraEdit see help page
Command Line Parameters and for more about using INIs see help page
INI File Selection and Advanced Settings.