New runtime items add to bottom of list

[oakleybrunt]

Problem

When adding a new runtime variable in the GUI (e.g. to the [directives] section), the new item is added to the top of the list. For jobs with large numbers of runtime variables, this can be quite irritating to add an item and then scroll up to set it.

For example, in the picture below you can see the new item has been added to the top of the list of set variables:

Proposed Solution

Can you make the "Add Item" button insert the new items at the bottom of the list?

[oliver-sanders]

There is a reason for the ordering, however, we may be able to do something to make the "add item" process less painful (ping @MetRonnie)

[MetRonnie]

The reason for adding at the start is that broadcasted env vars come before the existing ones in the config (64ae80b)

This makes it clearer you cannot define a new env var that depends on an already-defined one. This won't work as $BAR will be unbound when setting the value of QUX in the job script:

[oliver-sanders]

Could potentially move the Add Item button to the top of the list to resolve the UX issue.

[MetRonnie]

However I have noticed another problem: when adding more than one setting they probably ought to come in the order they were added (even if above pre-existing settings). For example, adding these two does not work:

Because you end up with:

cylc__job__inst__user_env() {
    # TASK RUNTIME ENVIRONMENT:
    export BAR FOO
    BAR="$FOO"
    FOO="foo"
}

Note you get the same confusing behaviour with

$ cylc broadcast wflow -n task -s '[environment]FOO=foo' -s '[environment]BAR=$FOO'
Broadcast set:
+ [*/task] [environment]FOO=foo
+ [*/task] [environment]BAR=$FOO

But the job script is the other way round, as above ☹️

[oliver-sanders]

Hmm, does broadcast purpusfuly apply from back to front?