# Windows--how to run new instance in a new window **URL:** \ **Category:** Factual Questions\ **Created:** [April 27, 2017, 11:46am UTC](https://boards.straightdope.com/t/windows-how-to-run-new-instance-in-a-new-window/785351 "2017-04-27T11:46:30Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [April 27, 2017, 11:46am UTC](https://boards.straightdope.com/t/windows-how-to-run-new-instance-in-a-new-window/785351/1 "2017-04-27T11:46:30Z")
Until the latest upgrade of Win 10, whenever I opened a new pdf file it opened in a new window. Now it simply replaces the previous one. I had often had three or four different pdf files and would go back and forth among them. With the latest upgrade, this behavior has changed. When I go to properties–advanced, there is a grayed out line about opening in a new memory space. It is actually shown clicked but is grayed out and cannot be chosen. Does anyone know how to restore the previous behavior? Incidentally, the pdf reader is Sumatrapdf. The Adobe reader is useless for someone like me who is continually recompiling LaTeX files. ---
**Author:** ![GreenWyvern](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/greenwyvern/32/2834_2.png) [@GreenWyvern](https://boards.straightdope.com/u/GreenWyvern)\ **Post date:** [April 27, 2017, 12:11pm UTC](https://boards.straightdope.com/t/windows-how-to-run-new-instance-in-a-new-window/785351/2 "2017-04-27T12:11:17Z")
This is to do with the way Sumatra PDF reader is written. You could check if they have a new version that works better with Win 10. Or you could switch to PDF-Exchange Viewer. It’s free, and the best PDF viewer I’ve come across. You can open as many documents as you like in separate tabs. If you click on a new document it will open in a new tab. [PDF-Exchange Viewer](https://portableapps.com/apps/office/pdf-xchange-portable) - Portable version [Web site](https://www.tracker-software.com/product/pdf-xchange-viewer) ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [April 27, 2017, 1:24pm UTC](https://boards.straightdope.com/t/windows-how-to-run-new-instance-in-a-new-window/785351/3 "2017-04-27T13:24:36Z")
I don’t know how to go back to the precise previous behavior, but at last for most programs you can start a new separate instance by middle-clicking its taskbar icon. ---
**Author:** ![Weisshund](https://avatars.discourse-cdn.com/v4/letter/w/ba8739/32.png) [@Weisshund](https://boards.straightdope.com/u/Weisshund)\ **Post date:** [April 27, 2017, 8:13pm UTC](https://boards.straightdope.com/t/windows-how-to-run-new-instance-in-a-new-window/785351/4 "2017-04-27T20:13:59Z")
pin sumatra to taskbar right click sumatera, in taskbar you will see sumatra listed in contect menu, right click that, click open. Should spawn a separate instance if the app will allow it Repeat as many times as needed. That should work for most any app that will allow multiple instances of itself. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [April 28, 2017, 12:38am UTC](https://boards.straightdope.com/t/windows-how-to-run-new-instance-in-a-new-window/785351/5 "2017-04-28T00:38:45Z")
Sumatra (version 3) has added the concept of tabs, where each document is in a different tab. That’s probably the difference. There is an option in the settings to turn off using tabs, which some report will cause it to open up each PDF in a new window. I can’t vouch for this, as I just use my old Adobe Reader 9 on Windows. Well that and the built-in reader in Firefox, since I mostly open PDFs online.