Idea: making Xnamespace usable from window managers (per-app isolation)

[probonopd]

Describe the idea

Expose Xnamespace in a way that window managers and desktops can use it at runtime to isolate individual applications.

A concrete example: a window manager provides a “Security / Isolate” button on a window. When triggered, that application (e.g. a browser) is placed into its own Xnamespace so it cannot interact with or observe other X clients.

It should be done because

Right now Xnamespace seems difficult to use from real desktop workflows. Namespaces are configured statically at X server startup and clients are assigned based on auth tokens at connection time.

This makes it hard or impossible for a WM to:

• Isolate a specific app on demand
• Expose Xnamespace as a user-visible security feature
• Avoid server restarts or predefining namespaces ahead of time

Making Xnamespace accessible at runtime would allow desktop environments to actually take advantage of the isolation it provides.

What are the alternatives?

• Edit configuration file
• Restart an application in order to move it into a namespace

None of these integrate as cleanly with X11 window managers as Xnamespace potentially could.

Additional context

From reading the code and docs, it looks like:

• Namespace membership is tied to Xauth tokens
• Namespace configuration is static and loaded at server startup
• There are no extension requests or client APIs for runtime namespace management

Some open questions I’m hoping to get feedback on:

• Is runtime namespace creation/assignment in scope for Xnamespace?
• Is there an intended WM-facing integration model that I may be missing?
• Would APIs for creating namespaces and assigning clients/windows be acceptable?
• Is hot-reloading namespace config something that could be supported?

Happy to help think through API design or implementation details if this idea aligns with the project’s direction.

Would be interested to implement this in the Gershwin WindowManager, gershwin-desktop/gershwin-windowmanager#47

Extra fields

• I have checked the existing New Ideas, RFCs Of The Core Team, Ideas Soon To Be Addressed and Someday Ideas
• I have read the Contributing Guidelines
• I'd like to work on this idea

[metux]

Yes, we definitively need an X11 extension for dynamically provisioning namespaces and moving clients between them.
Just didn't have the time to write a clear spec on this yet.

Feel free to make a draft :)

[PukPukov]

Isn't isolation the main selling point of wayland over x11? This could really be huge.

[metux]

Indeed. And they always claimed if couldn't be fixed in X11. But then: I came, saw and fixed it ;-)

Obviously, we don't have any dynamic provisioning yet (namespaces are statically configured on server startup), thats IIRC what this ticket is about.