Linear stepper behaving weird when going back a step

[Goodwine]

Bug, feature request, or proposal:

The stepper has weird styles when going back and leaving invalid steps, and it's inconsistent with the styles than when going back and leaving valid steps. It's also possible to have a combination of both where some labels will look disabled and some labels will look enabled when in fact they are all disabled.

What is the expected behavior?

On a stepper with 3 steps: A, B, C. If A, B and C are filled, valid and we are at C. When going back to B and making it invalid, it should mark C as disabled.
Then when going back to A and making it invalid too it should make B and C look disabled

What is the current behavior?

If B is made invalid, then A is made invalid too, B looks disabled but we can;t navigate there (because A is invalid), and C looks enabled even though we can't actually navigate there.

What are the steps to reproduce?

https://angular-qwtmdt.stackblitz.io

1. Fill requirements on Step 1.
2. Fill requirements on Step 2.
3. Fill requirements on Step 3.
4. Go back to Step 2 and erase a required field.
5. Go back to Step 1 and erase a required field.

What is the use-case or motivation for changing an existing behavior?

Behavior is inconsistent between steps 2 and 3. And Step 3 seems to promise that it's enabled when it's not, making the UI confusing.

[Goodwine]

@mmalerba

[Goodwine]

Hello, has there been any progress on this bug?

[mmalerba]

I haven't had a chance to look at this yet, but I can think of two possible ways for how it should work:

1. After invalidating step 2, the stepper should not allow you to move to another step until the step is valid again
2. It should allow you to go back to step 1 after invalidating step 2, but all steps following step 2 should be disabled until step 2 is fixed.

I think solution 1 is probably easier. I will probably try to make it behave like that unless someone has a good reason why solution 2 is the more correct behavior

[Goodwine]

The only possible reason I could imagine would be if there was a refresh button that caused step 1 and step 2 to be invalid.
My guess is that if I had that case, I should "manually" send the user back to step 1, so your first option would be fine then.

[Goodwine]

Hiya, has this been worked on yet?