CardExpander has inconsistent CornerRadius

[maihcx]

Describe the bug

CardExpander has inconsistent CornerRadius when opened and closed

To Reproduce

Set the CornerRadius property and click open the CardExpander

Video_2025-09-29_143024.mp4

Expected behavior

I want when setting CornerRadius property, when opening and closing the corner rounding is always consistent

Screenshots

No response

OS version

Window 11
Version 24H2 (OS Build 26100.6584)

.NET version

.Net 9

WPF-UI NuGet version

4.0.3

Additional context

No response

[maihcx]

I see this problem has been around for a long time with #867

[maihcx]

The problem lies in these 2 attribute code lines

wpfui/src/Wpf.Ui/Controls/CardExpander/CardExpander.xaml

Line 174 in 34c5392

CornerRadius="0,0,4,4"

wpfui/src/Wpf.Ui/Controls/CardExpander/CardExpander.xaml

Line 198 in 34c5392

<Setter TargetName="ToggleButtonBorder" Property="CornerRadius" Value="4,4,0,0" />