[SOLVED] Open file in existing instance of Visual Studio 2017

Open file in existing instance of Visual Studio 2017

I used to be able to open a file in an existing instance of VS - devenv.exe had a /dde switch for that.

But with VS2017 it opens the file in a new instance, not the one already running.

For example for json files:

My registry has a key HKEY_CLASSES_ROOT\.json\OpenWithProgids which contains a value VisualStudio.json.
And there is a key HKEY_CLASSES_ROOT\VisualStudio.json\shell\Open\Command which contains the default value "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\devenv.exe" /dde.

But that /dde is ignored.

Maybe all the betas and RCs corrupted something. My VS2017 is the latest updated version.

Does the /dde switch still work?

Solution

Okay what was missing was these:

HKEY_CLASSES_ROOT\VisualStudio.json\shell\Open\ddeexec\ with a default value of Open("%1").
HKEY_CLASSES_ROOT\VisualStudio.json\shell\Open\ddeexec\Application\ with a default value of VisualStudio.15.0
HKEY_CLASSES_ROOT\VisualStudio.json\shell\Open\ddeexec\Topic\ with a default value of system

All VS related files follow this pattern.