The custom control does not apply default style while it use as root element in xaml

[Daoting]

I'm submitting a...

• Bug report (I searched for similar issues and did not find one)

Current behavior

The custom control does not apply default style while it use as root element in xaml. When I set style by key in constructor instead of DefaultStyleKey, it's correct. The code:
public SingleWin()
{
#if UWP
DefaultStyleKey = typeof(SingleWin);
#else
Style = (Style)Application.Current.Resources["SingleWin"];
#endif
}

Expected behavior

Minimal reproduction of the problem with instructions

Environment

Nuget Package: 

Package Version(s): 
Uno.UI 1.40.0-dev.372

Affected platform(s):
- [x] iOS
- [x] Android
- [x] WebAssembly
- [ ] Windows
- [ ] Build tasks

Visual Studio
- [x] 2017 (version: )
- [ ] 2017 Preview (version: )
- [ ] for Mac (version: )

[Daoting]

xaml content like this:
<dt:SingleWin
x:Class="Dt.Sample.SamplesMain"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dt="using:Dt.Base">
...
</dt:SingleWin>

code-behind:
public sealed partial class SamplesMain : SingleWin
{
public SamplesMain()
{
InitializeComponent();
}
}

[jeromelaban]

Thanks for the report! DefaultStyleKey is not supported yet. it's forcibly using this.GetType() by default for now. I'll link this issue to #119.

[davidjohnoliver]

Fixed by #1766