VS Code Tabs Opening and NOT side by side (VSCODE)

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Summary

This postmortem analyzes a common Visual Studio Code frustration: files opening in new tabs instead of reusing the same editor pane. Although it feels like a bug, it is actually a predictable interaction between VS Code’s preview mode, split editor behavior, and user settings.

Root Cause

The root cause is almost always VS Code’s Preview Mode, which opens files in a temporary tab that is replaced when another file is selected.

Key contributors include:

  • workbench.editor.enablePreview set to true
  • Single-clicking files in the Explorer, which triggers preview mode
  • Accidentally dragging files, causing VS Code to open a new editor group
  • workbench.editor.openSideBySideDirection misconfigured, causing unexpected split behavior

Why This Happens in Real Systems

Real-world editors like VS Code optimize for speed and minimal clutter. That leads to:

  • Aggressive tab reuse to avoid overwhelming users with dozens of open files
  • Heuristics that assume “single-click = preview”
  • Implicit UI actions (like dragging) that create new editor groups without warning
  • Settings that interact in non-obvious ways, especially around tab management

Real-World Impact

Users experience:

  • Tabs opening in unexpected places
  • Files not staying open, causing confusion
  • Loss of focus, especially when navigating large codebases
  • Slower workflow, because the editor layout keeps shifting

Example or Code (if necessary and relevant)

Below is a minimal settings snippet that disables preview mode and forces VS Code to reuse the same tab unless explicitly told otherwise:

{
  "workbench.editor.enablePreview": false,
  "workbench.editor.enablePreviewFromQuickOpen": false,
  "workbench.editor.openSideBySideDirection": "right"
}

How Senior Engineers Fix It

Experienced engineers typically:

  • Disable preview mode to ensure deterministic tab behavior
  • Use double-click to pin tabs
  • Configure split behavior so side-by-side opens only when intended
  • Reset the layout when VS Code gets into a weird state
  • Use keyboard shortcuts (Ctrl+\ or Cmd+\) to explicitly control splits

They also understand that VS Code’s defaults are optimized for beginners, not for high-speed navigation.

Why Juniors Miss It

Junior developers often overlook this issue because:

  • Preview mode looks like normal tab behavior, so the distinction isn’t obvious
  • Settings are scattered, and the naming isn’t intuitive
  • They rely heavily on mouse navigation, which triggers preview mode more often
  • They don’t yet recognize when the editor is in a “split group” state

The result is a confusing experience that feels like VS Code is “fighting” them, even though it’s just following its default rules.

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