Add TrayIcon sample app

[logiclrd]

What does the pull request do?

Adds a sample application demonstrating the use of <TrayIcon> in App.axaml, including an associated menu.

TrayIcon.csproj optimistically references as-yet-nonexistent version 11.2.0 of Avalonia, in the hopes that it will include the bug fix for crashing when activating tray icon menu items.

UPDATE: 11.2.0 did indeed fix the problem, but this PR went to sleep for a while and now 11.3.8 is out.

Scope of this PR:

• fix or update to an existing sample
• add a new sample

Checklist

If this is a new Sample

• Added a ReadMe-file
• Updated the landing page
• Consider submitting a PR to https://github.com/AvaloniaUI/avalonia-docs with a link to your sample in the related documentation page

In any case

• Spell-checking done
• Checked if all hyperlinks work
• Checked if all images are visible

[timunie]

Hey @logiclrd,

I really have to apologize for not responding earlier. I wanted to wait for AvaloniaUI/Avalonia#7880 to be fixed but this seems to be more complicated than thought. Moreover your sample gave me some NRE that I didn't understand until today. And tbh, I forgot about this PR for quite a while.

Today I figured out that binding either directly to void or using RelayCommand will solve the NRE. So I think it's time to re-activate this PR.

[logiclrd]

Awesome 🙂 I've merged the latest in from the mainline, updated the changes here to follow changes to the README.adoc conventions that took place in the meantime, and then also updated the sample in a couple of small ways:

• It now also hooks the generalized "click" event, and the About window indicates how it was activated.
• The TrayIcon readme includes a small screenshot, since when the TrayIcon sample is run, the only visual change is the tray icon popping into the notification area, and that could be easily overlooked if the user doesn't know what they're looking for.

There was also a mistake in the directory name in the link from README.adoc to the TrayIcon sample.

I have verified that the changes to the .sln are correct using Visual Studio 2026.

[logiclrd]

Should I bump the references to Avalonia NuGet packages to a newer version? I'm sort of conflicted about this, because on the one hand, most of them are at the latest release version, but it's not 100% consistent and the version numbers that are there now happen to be the first version in which the sample runs properly.

But the majority of the samples are using 11.3.8, so the ones that aren't are probably just outliers that should be using 11.3.8. I'll bump the references. 🙂

[logiclrd]

Let me know if any other changes are needed. 🙂

[timunie]

Only these two comments to fix, otherwise it looks good to merge.

[timunie]

LGTM.

THX 🙏

[timunie]

Okay I screwed up now, so don't worry your changes have been merged just from the wrong branch 🙈