[dashboard] When adding two native filters (first ok,second one partially filled) I lost the first one

[adam-stasiak]

When I add two new filters and:

• first is correctly filled
• second is partially filled
  And I click on Save on first filter -> I do not get information that this SAVE will not keep my filter when I quit this modal.

Expected results

We should indicate that progress will be lost and:

• force user to finish or remove remaining filters before exit
• discard not valid filter entries
• keep them as draft not applicable for usage

@junlincc I think we should consider options for this.

Actual results

I do not get information that this SAVE will not keep my filter when I quit this modal.

Screenshots

Nagranie.z.ekranu.2020-12-22.o.00.01.28.mov

How to reproduce the bug

Enable Native filters
Go to filter adding on dashboard
I add two new filters and:

• first is correctly filled
• second is partially filled
  click on Save on first filter

Environment

docker
sha 90915db

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• [x ] I have checked the superset logs for python stacktraces and included it here as text if there are any.
• [ x] I have reproduced the issue with at least the latest released version of superset.
• [x ] I have checked the issue tracker for the same issue and I haven't found one similar.

Additional context

[agatapst]

Yeah, some info should be displayed here that first filter is not saved. I will take a look.