StatusNotifierHostRegistered DBus signal is not allowed, thus broken tray support on KDE Plasma

Hi @review-team, seems we need the desktop-legacy slot access to solve an issue with Telegram tray icon when it’s snap is autostarted by KDE Plasma desktop:

Telegram desktop sanp if built and published from their github repository ( already contains the desktop-legacy slot, which gets auto connected to the core. Hence, the issue has nothing to do with it.

Sorry I put it wrong.
The root of the problem is StatusNotifierHostRegistered DBus signal can’t be passed to snap, despite desktop-legacy slot, so changes to snapd seem needed:

tdesktop already has desktop-legacy slot. The problem is it doesn’t allow StatusNotifierHostRegistered signal. I.e. we need slot to be changed in snapd source code, not to be connected.