> 1) history is independent from "runs", we see a change, we apply it (even if it takes 10 sec or 2 minutes).
> 
> 2) "nothing should change during a run", we must process all changes before we start a run (starting a run takes forever),
>    and we must ignore changes during a run (i.e. updated frontend starts to write new data to history). (this is why
>    the trick to "start a new run twice" used to work).

"nothing should change during a run" violates the action when a user adds a new variable during a run. So if the user does that, they don't
care if things change during a run. Then we can also modify the history DB during the run. Note that some MIDAS installations are purely
slow control (kind of a replacement of LabView, have no runs at all). In those installations runs do not make sense at all, so keeping the
history independent of runs makes sense to me.

> It is "free" to rescan ODB every 10 second or so. Then we can output a midas message "please restart the logger",
> and set an ODB flag, then when user opens the history panel editor, it will see this flag
> and tell the user "please restart the logger to see the latest changes in history". It can even list
> the specific changes, if we want ot be verbose about it.

Sounds good to me.

> I say, let's take the low road for now and see if it's good enough:
> 
> a) have the history system report any changes in midas.log - "history event added", "new history variable added" (or "renamed"),
>    this will let user see that their changes to the equipment frontend "took" and flag any accidental/unwanted changes.
> 
> b) have mlogger periodically scan ODB and set a "please restart me" flag. observe this flag in the history editor
>    and tell the user "please restart the logger to see latest changes in the history".

Actually you don't have to actively "scan" the ODB. You have hotlinks to the logger anyway from the equipment variables. All we need 
in addition is a hotline to the settings array in the ODB. The logger receives the hotline update, checks if the names changed or got
extended, then flags this as a change.

Stefan