MasterDetailsView stays in the Master ViewState after resizing

[JulienTheron]

Hi,

I've discovered an issue with the MasterDetailsView control.
When the control is displayed on a window whose width is less than 720px, and then I expand the width of the window, the ViewState of the MasterDetailsView doesn't change. The ViewStateChanged event isn't raised, and the BackButton isn't shown (the MasterDetailsView is on the MainPage). If an item is selected in this state, the event is raised, and the BackButton is shown.

Note: This does not happen when a debugger is attached.

Thanks.

[skendrot]

Can you provide a repo? This is not reproducible with the sample app

[JulienTheron]

Hi just created a repo to reproduce the issue.
I subscribed to the ViewStateChanged event in order to auto-select the first item when the ViewState is Both.

Make sure not to be attached with a debugger when launching the app.
MasterDetailsView_Issue906

Thanks.

[skendrot]

Thanks @JulienTheron. I'll look into it

[yanxiaodi]

I found this problem too. I have writed a statetrigger to resolve it. I'll pull a request about this.

[skendrot]

@JulienTheron or @yanxiaodi can you confirm that the changes above fix this issue for you?

[JulienTheron]

Hi,

Still not fixed with the 1.4.0-dev00138 package.

I think the issue may come from the fact that there is a mismatch between the content of the VisualStateChangedEventArgs and stateGroup.CurrentState. Did you try passing VisualStateChangedEventArgs.NewState to the UpdateViewState method?

Thanks.

[yanxiaodi]

@skendrot I didn't use this control to implement my purpose. Because I need to control the state by the content of the detail panel, not only depends on the width of the window. When the content of the detail area is empty or not empty, the control's performance should be different. So I write a new state trigger to finish it.

[skendrot]

@yanxiaodi Can you give more details? What do you mean by "the controls performance should be different"? Does the ViewState property not meet your needs for controlling which state the control is in?

[h82258652]

@yanxiaodi How about this? https://github.com/h82258652/UwpMasterDetailViewSample
I think the MasterDetailView in this toolkit is too much complex. I have to create my own for my apps.

[skendrot]

@JulienTheron I still cannot reproduce the issue. I am doing the following:

private void MasterDetailsView_ViewStateChanged(object sender, UI.Controls.MasterDetailsViewState e)
{
    if (e == UI.Controls.MasterDetailsViewState.Both)
    {
        MasterDetails.SelectedItem = Emails.First();
    }
}