Visual Studio Code editor opens a new instance window on every double click on a file

Visual Studio Code is an Editor similar to the whole Visual Studio IDE, but just an editor with a
lot of plugins.

When VS Code is assigned as an editor to an extension, you can double-click on a file in an explorer
or other file manager and the file will be opened in the editor.

Per Default a new window instance is opened for every file you click.
The VS Code supports tabbed editing and to activate this also for opening files via the explorer you
have to set a user option.

The helpful link for me was found here

Open the User Settings via File->Preferences->User Settings and insert the following configuration:

    "window.openFilesInNewWindow": false,

After this all files are opened in a single instance window with tabbed display: