RadioButton is broken

[benstevens48]

I know there is now a RadioButtons control, but this is about using multiple RadioButton controls, which is still necessary to support certain layouts (e.g. RadioButton controls in a WrapPanel).

Bug 1 - can't set IsChecked in XAML
Consider the following XAML.

     <StackPanel>
            <StackPanel BorderBrush="Black" BorderThickness="1">
                <RadioButton Content="Radio button 1" IsChecked="True"></RadioButton>
                <RadioButton Content="Radio button 2"></RadioButton>
                <RadioButton Content="Radio button 3"></RadioButton>
            </StackPanel>
            <StackPanel BorderBrush="Black" BorderThickness="1">
                <RadioButton Content="Radio button 1"></RadioButton>
                <RadioButton Content="Radio button 2"></RadioButton>
                <RadioButton Content="Radio button 3" IsChecked="True"></RadioButton>
            </StackPanel>
        </StackPanel>

RadioButton controls without a GroupName are scoped to their parent, thus this should produce two independent sets of radio buttons. Want to guess what it initially looks like when you load a page containing this markup? Only the final radio button is checked. The first one is not checked. It appears that the radio buttons are put into their respective groups after the IsChecked property is set in XAML. Note the the radio buttons do subsequently work as two separate groups. The workaround is that you have to set IsChecked in code behind after the InitializeComponent of the page, which is annoying.

Bug 2 - GroupName is scope to the entire visual tree rather than the naming container
I'm not sure if naming container is the right word - I think this is what it was called at some point, but maybe it's now called definition scope or something like that. Suppose you create a set of radio buttons inside a UserControl, like this.

<UserControl x:Class="App2.MyUserControl2" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:App2">
    <Grid>
        <StackPanel BorderBrush="Black" BorderThickness="1">
            <RadioButton Content="Radio button 1" GroupName="UserControlRadios"></RadioButton>
            <RadioButton Content="Radio button 2" GroupName="UserControlRadios"></RadioButton>
            <RadioButton Content="Radio button 3" GroupName="UserControlRadios"></RadioButton>
        </StackPanel>
    </Grid>
</UserControl>

Suppose you use two copies of the UserControl in your main page, like this.

        <StackPanel>
            <local:MyUserControl2></local:MyUserControl2>
            <local:MyUserControl2></local:MyUserControl2>
        </StackPanel>

How do you think the radio buttons will behave? You'd think you'd get two independent sets of 3 radio buttons. In fact, you will get a single set of 6 radio buttons. Now it's possible this behavior is deliberate, but I really don't think so - would anyone really expect it to work like this? This effectively makes setting the GroupName property to a fixed value useless. The workaround is to create a new GUID after InitializeComponent in the user control, and then to set the GroupName of all the radio buttons to that, and then set the IsChecked property of the one you want. Technically, fixing this so the GroupName is scoped to the current naming container or definition scope or whatever it's called, would be a breaking change. If you think people are really relying on the existing behavior (which I find extremely unlikely), then please consider adding a ScopedGroupName property to RadioButton which is scoped to the current naming container.

These bugs make working with RadioButton controls very awkward (and these bugs have been there from the beginning - I did report them on UserVoice in the past but that didn't get any attention).

Windows 10 version	Saw the problem?
November 2019 Update (18363)	Yes

Device form factor	Saw the problem?
Desktop	Yes

[marcelwgn]

Those seem to valid issues.

If the only reason RadioButtons is not issue is the fact you can't change the layout, you might want to retemplate the RadioButtons control and use a different layout internally.

We might want also want to make the layout of the internal ItemsRepeater a property, so that does not require retemplating.

[ranjeshj]

@YuliKl @StephenLPeters as FYI. Exposing the Layout property on RadioButtons is an option.

[marcelwgn]

@ranjeshj Should we open a proposal for that (adding a layout property to RadioButtons)?

[ranjeshj]

@ranjeshj Should we open a proposal for that (adding a layout property to RadioButtons)?

Yes. Please.

[benstevens48]

Thanks for the comments. This issue was intended to be mainly about fixing bugs with the individual RadioButton control - I hope it can stay focused on that. I think there will always be situations (possibly quite rare) where individual RadioButton controls have to be used, and since frameworks like HTML have this control, I think it should continue to be supported.

Regarding the comments about the WinUI RadioButtons control. In my case I have RadioButton controls inside a custom WrapPanel control. If it the RadioButtons template was happy with an ItemsControl replacing the ItemsRepeater, then I could re-template it to make use of my custom WrapPanel, using it as the ItemsPanel in the ItemsControl. (I haven't tested whether this works or not). Exposing the Layout property would be another solution, but then I'd have to refactor the layout logic of my control so that I could be used as the Layout property, which would be a bit awkward.

[ranjeshj]

@benstevens48 Yes. I am following up to understand the issues with RadioButton. I believe one of the reasons for the RadioButtons control in the first place is because of the automation experience when using GroupName. RadioButtons provides a better automation experience (Narrator) for that scenario.

ItemsRepeater and ItemsControl do similar things, so if you are writing a custom WrapPanel, it is possible to do the same for WrapLayout (deriving from NonVirtualizingLayout). There is also a LayoutPanel in the preview which can get you the same behavior of WrapPanel (LayoutPanel has a Layout property that you can feed in the same layout object).

[StephenLPeters]

Unfortunately these RadioButton issues won't be able to be fixed without winui 3.

[StephenLPeters]

@benstevens48 Since we will not be able to fix these issues for a while, you might be able to work around this issue by setting the checked radio button from code behind in the on apply template callback.

[benstevens48]

Thanks, yes I have already been using this workaround (setting after InitializeComponent) for several years, I just wanted to report it so that hopefully it can get fixed eventually.