[Desktop] Add support for system tray icons

[proninyaroslav]

Related to: google/flutter-desktop-embedding#595

Use case

The tray icon is an important part of many desktop applications that run in the background.

Proposal

This can be implemented as a official plugin.

Main features:

• Position of the icon
• Setting icon as monochromatic template image is needed on macOS so it can support dark mode
• Allow text instead of the icon or in addition to the icon. I don't know if this is possible on Linux or Windows but macOS allows this.

[iapicca]

@proninyaroslav
not a desktop expert, but aren't some of these features already available acording to this tweet

Hey @FlutterDev gang: what if I told you you can use any widget as an icon of your macOS app and even change it in runtime 🤯?
Here's a quick demo 🎬
⚠️ Next goal: animated icons from image sprites pic.twitter.com/3RgyyOQeXy

— Andrei Lesnitsky 💙 (@lesnitsky_dev) April 27, 2021

[proninyaroslav]

@iapicca
This is part of the dock, but not the tray. Although on macOS apps can use the dock as a background work indicator, but:

1. This is exclusively in macOS, other OS usually use the tray.
2. The tray has more customization options.

[iapicca]

This is part of the dock, but not the tray. Although on macOS apps can use the dock as a background work indicator, but:

1. This is exclusively in macOS, other OS usually use the tray.
2. The tray has more customization options.

@proninyaroslav oh... my bad

[stuartmorgan]

For macOS the equivalent would be a menu extra. See discussion and screenshots in the issue referenced in the description.

[tawanda]

There is this https://pub.dev/packages/system_tray

[ggdream]

https://pub.dev/packages/system_tray

system_tray works, but it does not support important operations such as minimizing, opening, and exiting. His example references bitsdojo_window.

It is true that bitsdojo_window can satisfy the effect, but the shortcomings are also very obvious:

• Code injection is very invasive, and the original built-in code should be manually modified.
• Removed the default top bar, but in many cases it needs to be retained, which is not reasonable.

[lijy91]

@ggdream
You can use tray_manager and tray_manager.

[flutter-triage-bot]

The triaged-desktop label is irrelevant if there is no team-desktop label or fyi-desktop label.