maui Inheriting Visual States

trafficstars

Description of Change

Visual states from parent types aren't being applied to derived types.

I have a button that when clicked switches between a Normal and a Custom state: VisualStateManager.GoToState(button, !isNormal ? "Custom" : "Normal");

Everything works as expected when both states are defined in the same VisualStateGroup:

<Style TargetType="Button">
    <Setter Property="VisualStateManager.VisualStateGroups">
        <VisualStateGroupList>
            <VisualStateGroup x:Name="CommonStates">
                <VisualState Name="Normal">
                    <VisualState.Setters>
                        <Setter Property="TextColor" Value="White" />
                        <Setter Property="BackgroundColor" Value="Black" />
                    </VisualState.Setters>
                </VisualState>
                <VisualState Name="Custom">
                    <VisualState.Setters>
                        <Setter Property="TextColor" Value="Red" />
                        <Setter Property="BackgroundColor" Value="Green" />
                    </VisualState.Setters>
                </VisualState>
            </VisualStateGroup>
        </VisualStateGroupList>
    </Setter>
</Style>

The issue occurs when one of the visual states is defined in the parent Style. In that context the Custom style is ignored - the same happens when the visual state is defined in the global styles.

<Style TargetType="Button" x:Key="parentStyle">
    <Setter Property="VisualStateManager.VisualStateGroups">
        <VisualStateGroupList>
            <VisualStateGroup x:Name="CommonStates">
                <VisualState Name="Custom">
                    <VisualState.Setters>
                        <Setter Property="TextColor" Value="Red" />
                        <Setter Property="BackgroundColor" Value="Green" />
                    </VisualState.Setters>
                </VisualState>
            </VisualStateGroup>
        </VisualStateGroupList>
    </Setter>
</Style>

<Style TargetType="Button" BasedOn="{StaticResource parentStyle}">
    <Setter Property="VisualStateManager.VisualStateGroups">
        <VisualStateGroupList>
            <VisualStateGroup x:Name="CommonStates">
                <VisualState Name="Normal">
                    <VisualState.Setters>
                        <Setter Property="TextColor" Value="White" />
                        <Setter Property="BackgroundColor" Value="Black" />
                    </VisualState.Setters>
                </VisualState>
            </VisualStateGroup>
        </VisualStateGroupList>
    </Setter>
</Style>

This PR is supposed to fix it by adding the visual state that has not been defined in the derived style from the parent style to the derived style