Windows 10: multiple instances of a chat program

Programs like EXCEL and WORD allow more than one instance to be open on the desktop simultaneously; is there a structural reason why a chat program could not have a separate instance open for different contacts ?

:)

 

Windows 10 Virtual Desktops and multiple program instances

I'm having an issue with the new Virtual Desktops in Windows 10. For example:

1. From Desktop 1, double click the file "test1.xlsx". This will open the file in a new instance of Excel (specifically 2010, in my case), on Desktop 1.
   
2. From Desktop 2, double click the file "test2.xlsx". This will change the desktop to Desktop 1 and open the file in the same instance of Excel as from step 1.
   

I've found this to also be true with Notepad++, so my guess is that this behavior occurs with any program that opens multiple files in a single instance. However, these are the two programs I generally use in this way.

I've found a number of ways to disable DDE for Excel, but this isn't what I want to do. If I open a second file from a desktop that already contains an instance of the program that should open it, I want to use that instance.

I've found manual ways of opening a second instance, moving it to the correct desktop, and then opening the file in that instance. However, the process is slightly different for each program and overall is, at best, clunky. Not to mention that now a third file will open in the most recently used instance, and not necessarily the correct one, requiring the whole process to start over again.

 

How to prevent multiple instances of an application

the only time that works is when the program itself is written to prohibit multiple instances

if the programmer didn't do that with this program

then there really isn't any method to preventing multiple instances

 

Multiple instances of a program open with different window size?

I frequently open multiple instances of the Arduino IDE program. The first opens to the same size as the window was when I closed it. Subsequent opens of new instances of the program (it's not unusual for me to have three or four instances running at the same time) open in a much smaller window. Is this normal?

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