Use systemd tray.target

[budimanjojo]

Description

This make waybar systemd unit to be part of tray.target. So it's uniform with the other bars and make working with tray applets easier. Related changes to other bars: 4f70f49

Checklist

• Change is backwards compatible.

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[Scrumplex]

Isn't this racy?
Other services could also start as they might be wanted by tray.target, before waybar has even initialized.

[cyntheticfox]

I guess short of having those services instead depend on waybar.service, you'd have to create a tray-pre.target, which would make sense to me if people are pinning tasks that go into a tray to tray.target, and they as such need a tray service to pre-exist to put it in.

[stale]

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