set default duration for messages in the left sidebar status bar

[redshiftzero]

Description

In the status bar at the bottom of the application, the status bar messages have a default duration.

We should implement this for the status bar at the left sidebar of the application:

[ninavizz]

In the way @ntoll has the QT app setup right now, are these messages placeholders for what will eventually be experienced by users as transient (or, "toast") notifications (my interpretation from the above screenshot)?

Goal in asking this: is the longer-term interest to establish a default auto-expire timing for transient/toast notifications?

Transient/toast notifications should display for 5 seconds at 100% alpha, then fade-out to 0% over 2 seconds. The fading-bit, If possible. If not, then just 5 seconds should be the default. Longer messages will require more time, but no message should display for fewer than 4 or 5 seconds.

4 seconds is what Google recommends in their Material design spec, and other articles I've read cite 5.

[eloquence]

I'm assuming this can be closed since we now have a single status bar at the top which does appear to consistently go away after a few seconds; please reopen if this is still relevant.