Fluent Theme: Controls inside `ToolBar` have poor styling and usability

Description

When creating a desktop application with the new Fluent theme of .NET 9, controls inside the ToolBar appear poorly styled and have low usability. For example, one cannot see if a CheckBox is checked or a ToggleButton is toggled. Also the styling does not appear not up-to-date with the Fluent theme.

Reproduction Steps

Create a .NET 9 desktop app with the new Fluent theme
Add a ToolBar like so:

<ToolBarTray Margin="0,10,0,0">
    <ToolBar DockPanel.Dock="Top">
        <Button>Button</Button>

        <ToggleButton Margin="5,0,0,0" IsChecked="True">Checked Toggle Button</ToggleButton>

        <CheckBox Margin="5,0,0,0" IsChecked="True">Checked CheckBox</CheckBox>

        <ComboBox Margin="5,0,0,0">
            <ComboBoxItem IsSelected="True">ComboBox</ComboBoxItem>
            <ComboBoxItem>Bar</ComboBoxItem>
            <ComboBoxItem>Baz</ComboBoxItem>
        </ComboBox>

        <ComboBox Margin="5,0,0,0" IsDropDownOpen="True">
            <ComboBoxItem IsSelected="True">Open ComboBox</ComboBoxItem>
            <ComboBoxItem>Bar</ComboBoxItem>
            <ComboBoxItem>Baz</ComboBoxItem>
        </ComboBox>
    </ToolBar>
</ToolBarTray>

Expected behavior

Controls in the ToolBar are well-styled and have fair usability.

Actual behavior

Controls in the ToolBar are poorly styled and have low usability:

Regression?

No response

Known Workarounds

No response

Impact

Writing desktop apps with the new Fluent theme of .NET 9 requires either restyling controls or simply not using standard controls. The palette of realistically usable controls is smaller than expected.

Configuration

Property	Value
SDK	.NET 9 RC2
OS Name	Microsoft Windows 11 Pro
Version	10.0.22631 Build 22631
System SKU	Surface_Pro_8_1983

Other information

No response

dotnet / wpf