Bug in Session view: Popup with labels is not updated.

[idealist1508]

To reproduce:

1. open sesion view
2. open Edit Labels... dialog
3. add new label and save
4. right click to add label to the session => the new label is not listed in this popup

[alex-hhh]

This is one of the many cases where the GUI consistency is still not maintained correctly when data changes. The workaround in this case is to use the "View/Refresh..." menu. There are other cases when such inconsistencies happen, in particular the same thing would happen for the equipment.

I didn't work on these cases, because I considered this case to be infrequent: I would expect users to rarely define labels, and when they do, they either need to refresh the session view or re-open the session, but other than that, the label would be available.

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The overall approach to GUI consistency is described in gui-consistency.md, and for this to work we would need to:

• decide on the name for the new event, say 'labels-changed
• update the labels editor to call (log-event 'labels-changed #f), perhaps when they are saved
• add a demand-callback to the menu item to look for 'labels-changed events. The menu is created here, but there are two classes derived from tag-input-field%: label-input-field% and equipment-input-field%. You can see how "listening" for these events is implemented by searching for make-log-event-source, for one example, see here -- note that each listening is done slightly differently, some use a separate thread, but in this case, we can just check in the demand-callback if the 'labels-changed event was posted and update the menu before showing it.

[alex-hhh]

This is a corner case and a workaround is available. Given that I don't have time to work in this, I will close it.