Add "Mirror panel to display" option in Panel Settings

[mike277202]

Currently, Cinnamon has no native way to mirror a panel's applet layout across multiple monitors. Users with multi-monitor setups must manually recreate their panel on each display by individually adding applets one by one, and there is no way to keep them in sync.

Problem

When a second panel is added to a second monitor via Panel Settings, it starts completely empty. There is no option to copy or mirror the existing panel layout.

Proposed Solution

Add a 'Mirror panel to display' button inside the Panel Settings window that:

Detects all connected monitors via xrandr

Allows the user to select a target monitor and panel position

Copies all compatible applets from panel 1 with new unique IDs

Skips single-instance applets (systray, network, sound) gracefully, as their max-instances is set to 1 in metadata.json

Mirrors icon size and zone settings to match the source panel

Proof of Concept

I have written a working Python script that implements this logic in full using dconf reads/writes outside of the Cinnamon codebase. It has been tested on a dual-monitor setup running Linux Mint with a NVIDIA GPU

The script is available here: https://gist.github.com/mike277202/3a33068373b965a642e43518b4b48156

I'm keen to take this further and integrate it natively into the Cinnamon codebase across panelManager.js, appletManager.js, and cs_panel.py. Would welcome any guidance from maintainers on the best approach before submitting a PR.

Environment

Linux Mint (latest)

Cinnamon desktop - Cinnamon 6.6.7

Dual monitor setup

[mike277202]

I have updated the script to remove the hard coding of 2 monitors it now detects all connected monitors via xrandr and allows the user to copy the panels to more than one other monitor

mirror-panel-0.0.5.py

[klangman]

You're so close.. Why not just convert your Python to a Javascript Cinnamon extension. You can then add a Panel menu item that copies the applets from the Popup menus panel to all Panels that are completely empty of Applets.

[mike277202]

I have done close to what you suggested and converted it to javascript - made it as a applet as that seemed appropriate, I have submitted a pull request let me know if theres anything I need to fix :)