You cannot use the ITypeEditor inside your EditorDefinition.
When using the EditorDefinition approach, you must put your UI inside your template.
ex:
When using the EditorDefinition approach, you must put your UI inside your template.
ex:
<xctk:EditorDefinition.EditorTemplate>
<DataTemplate>
<Grid>
<!-- Rebuild your editor here in XAML instead of code --->
</Grid>
</DataTemplate>
</xctk:EditorDefinition.EditorTemplate>
