MatTabGroup: What is the current purpose of the ActiveIndex property? Can its functionality be extended?

[jweschenfelder]

Describe the feature request MatTabGroup does not show the currently active tab after setting the tabIndex via ActiveIndex property in code behind, e.g. via <MatTabGroup @bind-ActiveIndex="@tabIndex"> or <MatTabGroup ActiveIndex="@tabIndex"> or <MatTabGroup ActiveIndex="2">.

Expected behavior I wish the setting ActiveIndex="@tabIndex" would have some functionality so that it switches to Tab 3 on the GUI automatically if I set <MatTabGroup ActiveIndex="2"> in the code behind.

Screenshots

Links to reproduce the issue Link: https://blazorfiddle.com/s/jo72rp45 or https://www.matblazor.com/Tab (3rd example 'Dynamically set tab index')

Remarks It was already reported in https://github.com/SamProf/MatBlazor/issues/633 in the past. But I think it would be a great feature if the MatTabGroup would do the refresh on its own by default without I have to call StateHasChanged();. Update: Even if I call StateHasChanged();, it does not work for me: The ActiveIndex property is simply ignored.

[jweschenfelder]

Update: I just noticed that all MatTab components have tabindex="0" when rendered in a for or foreach loop, the tabindex is not incremented. I would think now that someone had started to implement the ActiveIndex property, but that the implementation never was finished.

When rendering two MatTab's within a for loop inside of MatTabGroup, both MatTabs will have the same tabindex: