Preliminary Checks

• I have read and understood the important section above.
• I have searched existing issues and avoided creating duplicates.
• I am not filing an enhancement request.
• I have checked that this issue cannot be reproduced on Mozilla Firefox.
• I have checked that this issue can be reproduced once I removed all my Mods and Custom CSS.

What happened?

When the Library window (opened with Ctrl + Shift + O) is left open and the main browser window is closed first, closing the Library window afterward causes all previously open tabs and windows to be lost.
Even if “Open previous windows and tabs” or “Continue where you left off” is enabled, reopening Zen Browser starts with no restored tabs.

Possibly related to session handling when non-main windows are closed last?

Expected behavior

Browser should restore the previously opened tabs and windows according to session restore settings.

Actual behavior

Browser opens with no restored tabs — session data seems to be lost if the main window is closed before the Library window.

Steps to reproduce

1. Open Zen Browser.
2. Open several tabs.
3. Press Ctrl + Shift + O to open the Library window.
4. Close the main browser window (keep the Library window open).
5. Close the Library window.
6. Reopen Zen Browser.

Screenshots and videos

No response

Version

1.17.3b

What platform are you seeing the problem on?

Windows - x64

What component is this issue related to?

Tabs

Relevant log output if applicable