How to Use Your Tablet as a Second Monitor on Ubuntu

I’m surprised just how easy it is to use an iPad or an Android tablet as a second monitor with Ubuntu 22.04 LTS.

Not just “access your desktop” but “use it to extend your desktop” as though it were a normal, physically connected external monitor.

I know I’m supposed to be on the pulse when it comes to stuff like this. Yet here I am, monsieur slow-train, only learning about this capability because I saw it mentioned on Reddit.

Naturally I had to try it out for myself. I’ve wanted this sort of capability on Linux for a long time, albeit not out of any major need for a second monitor more the satisfaction of knowing “anything Apple can do…” Linux can do better, etc 😉.

Good news: it works pretty well — see it in action in this (hastily recorded) video:

GNOME developers are to thank for this.

Among the many new GNOME 42 features were changes to remote desktop protocol (RDP) and screen sharing support. Amongst this, the ability to extend the GNOME Shell desktop to a virtual monitor as though it were a real one (and respect multi-monitor preferences).

Latency is a big ask. Using a tablet as an external monitor through RDP is an entirely different use case to simply accessing a desktop over RDP (which can be very laggy).

To help, GNOME devs plumbed in frame-tracking and enhanced hardware acceleration. This delivers a smooth-as-possible experience (though as the feature is network dependant don’t expect flawless fluidity on poor/slow connections).

In a nutshell, any Linux distro with GNOME 42 (or above) can use any RDP-supported device (e.g., Android tablet, iPad, even another computer) as an external monitor, similar to Apple’s SideCar feature (which lets macOS lets users extend their desktop to an iPad screen wirelessly).

Virtual monitors behaves like regular monitors so if you’re using one to extend your desktop you can ‘drag’ it to your preferred location from the Settings > Display panel, and adjust your virtual monitor’s screen resolution independently of your “main” display.

While this sort of feature is not ‘new’ new — it’s been possible to use tablets as external monitors (including on Linux) via the local network for a while — what is new is that all of relevant components to make this work are baked into GNOME desktop now.

Let’s look at how to set it up.

Enable Virtual Monitors in GNOME

Before you do anything make sure you are using Ubuntu 22.04 LTS or a Linux distribution based on GNOME 42 or later. The parts that make this possible aren’t included in earlier versions. While I tested in a Wayland session this should work in Xorg too, but YMMV.

First, open a Terminal window and run: gsettings set org.gnome.desktop.remote-desktop.rdp screen-share-mode extend.

This step is needed to enable extendable virtual monitors over RDP because, at present, the feature is hidden (and not polished enough for the masses to make use of yet — so be aware).

Next, open the Settings app, navigate to the Sharing panel, and turn on Sharing, and turn on (once it appears) the ‘Remote Desktop’ option. You will want to set up a username and password too, to allow you to connect from a different device.

Use an RDP client on your tablet/phone — I used Microsoft’s free Remote Desktop Mobile which is available for Android and iOS — to connect to your computer from your tablet using your local IP¹ (plus the right login credentials, if set previously).

In Microsoft’s app just tap the “+” icon, enter your PCs IP address_¹, and the user credentials you created previously. Make sure you hit the ‘save’ button before backing out or you’ll have to do it again.

Now from the main screen of the app tap on the listed thumbnail to connect and hey, presto!

Finally, head back to the Settings > Display panel to reposition your virtual monitor, configure the screen resolution, etc. Remember: any multi-monitor behaviours you’ve tweaked elsewhere (e.g., ‘show dock on all monitors’) are respected by virtual monitors too.

A few caveats

Once connected through an RDP app on the second screen everything should “just work”.

Don’t get carried away, mind: you can’t use your virtual monitor as, say, a playback monitor when video editing because the frame rate isn’t 100%. Also, you can’t use touch events on the tablet to interact with any windows or desktop environment either, nor something like an Apple Pencil.

You will also see a second cursor on the virtual monitor. This doesn’t “work” (though you can move out of the way). This is a bug at present and will be fixed in a future GNOME update.

Also make sure that when you’re not using this feature to turn off remote desktop in the sharing app. While it’s unlikely anyone will be local-enough to access your computer, it’s a possibility.

1. To find your IP in Ubuntu go to Settings > Network, click the cog icon next to the active network, and locate your IP in the ‘details’ pane. ↩︎