The following example shows how to create a ChildWindow and a MessageBox within a WindowContainer.
<xctk:WindowContainer>
<xctk:ChildWindow WindowBackground="Blue"
Left="75"
Top="50"
Width="275"
Height="125"
WindowState="Open">
<TextBlock Text="This is a Child Window" Padding="10"/>
</xctk:ChildWindow>
<xctk:ChildWindow WindowBackground="Green"
Left="175"
Top="125"
Width="275"
Height="125"
WindowState="Open">
<TextBlock Text="This is another Child Window" Padding="10"/>
</xctk:ChildWindow>
<xctk:MessageBox Caption="MessageBox"
Text="This is a MessageBox"/>
</xctk:WindowContainer>
.NET: net5.0, net5.0-windows, net6.0, net6.0-macos, net6.0-windows, net7.0, net7.0-macos, net7.0-windows, net8.0, net8.0-browser, net8.0-macos, net8.0-windows, net9.0, net9.0-browser, net9.0-macos, net9.0-windows, net10.0, net10.0-browser, net10.0-macos, net10.0-windows.
.NET Framework: net40, net403, net45, net451, net452, net46, net461, net462, net463, net47, net471, net472, net48, net481.