When you [single-]click a file in the left sidebar's file browser or open it from the quick open menu (Ctrl-P, type the file name, Enter), Visual Studio Code opens it in what's called "Preview Mode", which allows you to quickly view files.

Preview Mode tabs are not kept open. As soon as you go to open another file from the sidebar, the existing Preview Mode tab (if one exists) is used. You can determine if a tab is in Preview Mode, by looking at its title in the tab bar. If the title is italic, the tab is in preview mode.

To open a file for editing (i.e. don't open in Preview Mode), double-click on the file in the sidebar, or single-click it in the sidebar then double click the title of its Preview Mode tab.

If you want to disable Preview Mode all together, you can do so by setting "workbench.editor.enablePreview": false in your settings file. You can also use the "workbench.editor.enablePreviewFromQuickOpen" option to disable it only from the quick open menu.

Before you can disable Preview Mode, you'll need to open your Settings File.

Pro Tip: You can use the Command Palette(shortcut Ctrl+Shift+P) to open your settings file, just enter "Preferences: Open User Settings"!

Once you've opened your settings file (your settings file should be located on the right), add the "workbench.editor.enablePreview" property, and set its value to false.

You can learn more about Visual Studio Code's "Preview Mode" here.
See also article How to Always Open Files in a New Tab - VSCode

I came up with the same problem, and open setting.json file, add the following:

"workbench.editor.enablePreview": false

If you don't want to disable preview mode you can explicitly tell vscode to keep a specific tab open. As mentioned above a tab heading with italic text is in preview mode.

To get a tab out of preview mode you can either right click on the tab and choose keep open or use the shortcut cmd + k enter that is mapped to the command workbench.action.keepEditor.

Furthermore, double-clicking on a tab also gets it out of preview mode (verified in vscode 1.44.0).

For 2020:

easy as pie, tap preferences (command ⌘ + , on Mac),

The secret is "Enable preview"

they added it right there:

Turn OFF (uncheck) for NORMAL behavior.

i.e., Turn OFF to avoid the "automatic closing" behavior.

Use workbench.editor.enablePreview: false to disable Preview mode completely.

Use workbench.editor.enablePreviewFromQuickOpen: false to disable Preview mode for the files open from quick open menu.

Open in new Tab Solution:

1. Open the command palette by: Cmd + Shift + K
2. Open settings file by: Preferences: Open Settings (JSON)
3. Under user setting, enable Tabs by: "workbench.editor.showTabs": true

Watch for filenames in italic

Note that, the file name on the tab is formatted in italic if it has been opened in Preview Mode.

Quickly take a file out of Preview Mode

To keep the file always available in VSCode editor (that is, to take it out of Preview Mode into normal mode), you can double-click on the tab. Then, you will notice the name becomes non-italic.

Of course, you can simply double-click to open a file. This will open the file in a new tab, skipping the Preview Mode.

Feature or bug?

I believe Preview Mode is helpful especially when you have limited screen space and need to check many files.

For anyone who don't want to disabled Preview Mode.

As I read whole of comments and I found what I preferred that is the shortcut key to pin the opened file from Quick Open/Ctrl+P or that's mean to keep the opened file to the editor, and yes also don't need to switch your hand to the mouse to double-click on files list.

Thanks to @jontem and @MattLBeck.

Call save command with Ctrl+S (⌘+s on Mac) is the easiest way to reach what I preferred.

And if you found out you do this to keep opened file to editor quite frequently, yes I preferred you should setting the option "workbench.editor.enablePreview": false or "workbench.editor.enablePreviewFromQuickOpen": false as others mentioned before.

⚡ Actually, VSCode shows you the preview of a file.

You can disable the preview with this:

"workbench.editor.enablePreview": false,

⬇️ Basically just add these two settings and you're good to go.

Menu File → Preferences → User Settings: add this line

"workbench.editor.enablePreviewFromQuickOpen": false

If you want to open a file permanently from "Go To File..." (⌘P), press "right arrow" instead of return.

This also keeps the Go To File... search bar open so you can quickly open multiple files.

This is not a new answer. It is just showing how to do it via UI. Open settings via File => Preference => Settings. The most upvoted answer is the correct choice.

Then in search field type Preview.

After that select Workbench and look for Enable preview options.

Uncheck the boxes.

From settings you can find edit settings.json You need to search by Preview. Please check the below screen short.

Add the below code there:

"workbench.editor.enablePreview": false 

You can do it via GUI

Search for preview

uncheck the options Enable Preview and Enable Preview from Quick Open

Essentially, there are three settings that one has to update (Preference >> settings):

• workbench.editor.enablePreview: set this to globally enable or disable preview editors

• workbench.editor.enablePreviewFromQuickOpen: set this to enable or disable preview editors when opened from Quick Open

• workbench.editor.showTabs: finally one will need to set this
  otherwise, there will be no tabs displayed and you will just be
  wondering why setting/unsetting the above two did not work

enabling using GUI

go to Code -> Preferences -> Settings -> User -> Window -> New Window

here Open Files In New Window under drop down list select "on" that's it.

my VS Code version 1.38.1

1. Double-click your files instead of single-clicking.

• Instead of single clicking on your files, (like I do in the previous GIF) double-click. This will tell VS Code that you want the file to stay open when you switch to a new file.

• Here's my beautiful demonstration of this:

2. Double-click the tab you want to keep open

• This works if the tab you are working with is in "Preview Mode" (italicized) and you want it to stay open when you open another file.

3. Right click your tab and select "Keep Open"

• This one's self-explanatory. Simply right-click on the Preview Mode tab on the tab at the top of your screen (while it's italicized) and click on "Keep Open" once the context menu pops up.

• Here's my beautiful demonstration of this:

When you single-click a file in the left sidebar's file browser or open it from the quick open menu (Ctrl-P, type the file name, Enter), Visual Studio Code opens it in what's called "Preview Mode", which allows you to quickly view files.

It's a feature, not a bug.

• Very often while programming you will only need to open a file for a small window of time, to "preview" its contents.

FOR MORE INFO

You need to edit settings.json file, which is located at:

Windows %APPDATA%\Code\User\settings.json
macOS $HOME/Library/Application Support/Code/User/settings.json
Linux $HOME/.config/Code/User/settings.json

{
  "workbench.editor.showTabs": true,
  "workbench.editor.enablePreview": false
}

As hktang above indicates:

one Click opens the file in preview mode (header text in italics)

Double click the same file, it goes out of preview-mode (header text changes from italic to normal font)

I think this is a "comprimise" feature allowing users, to "navigate" both worlds; preview and none-preview.

• All you do is click the file to open it in the right panel.
• Then immediately double click it to keep it there.
• Or - just treble click. File opens in none preview mode.

HTH Paul S.

• Go to File > Preferences > Settings
• Search for workbench.editor.enablePreviewFromQuickOpen
• Set it to false or uncheck it.

For those who using Windows OS:

• Press Ctrl + Shift + P
• Select Preferences: Open Settings (JSON) from the list
• Select all and Paste this { "workbench.editor.enablePreview": false }

That's it now it will open in a new tab instead of replacing on the existing one.

For reference look at the screenshot below:

to open another file in a new tab keeping the current file open,

• first double click (left click) the current file
• then click (single click) the new file

in this way, the new file will be opened in another tab

#OR

you can drag the new file from vs code project explorer and drop it beside opened tab, exactly where the new tab will be opened

Actually, VSCode shows you the preview of a file when you open it. If you want to open files in a new tab, just disable the preview with this setting (paste this in the settings.json file).

"workbench.editor.enablePreview": false, 

— you can take it one step further and use this setting

"workbench.startupEditor": "newUntitledFile",

— It will open your VSCode editor with a blank new untitled file to quickly get started.

Simple and Best way is whenever you open new file it is in preview mode so simply press the CTRL + K and then press ENTER then you done with preview mode , Now this file will remain always open until you closed it that's what you need to do ....

One simple solution is, instead of making changes in settings of vscode, whenever you open a file through a reference,you will see that the file is in preview mode(the name of file is in italic) and in the sidebar you will see that same preview file in focus just double tap it and it will be pinned on the tab,so that it wont get replaced by another file in preview mode.

In my case, I also had to set workbench.editor.showTabs property to true (in addition to workbench.editor.enablePreview)

I'm not sure how it got changed to false. Maybe, I've accidentally set it to false using some shortcut.

This is so confusing. All developers I asked didn't appreciate this default behavior.

I use cmd + P to open project files.

Settings -> Workbench -> Editor Management -> Enable Preview

for me, shift + enter did the trick.

In my case I had accidentally changed the setting for viewing files in tabs and didn't know where to look to change back to the behavior I was used to i.e. double clicking on the files name in the file explorer pane (typically LHS) to open the file in a new tab.

There is a setting to check or uncheck "enable tabs".

In VS Code 1.77.3 you can click on the 3 dots on the RHS (see image below)

Note: Full version info of my VS Code installation: Version: 1.77.3 Commit: 704ed70d4fd1c6bd6342c436f1ede30d1cff4710 Date: 2023-04-12T09:16:52.732Z Electron: 19.1.11 Chromium: 102.0.5005.196 Node.js: 16.14.2 V8: 10.2.154.26-electron.0 OS: Linux x64 6.2.0-20-generic snap Sandboxed: Yes