How do I create a full-trust XAML Browser Application?

If you want to take advantage of functionality that requires a higher level of trust yet still want
to be integrated into a browser,you can indeed configure an XBAP to require full trust. The
two actions to enable this are a bit convoluted,however:
1. In the ClickOnce application manifest (app.manifest),add Unrestricted=”true” to
the PermissionSet XML element. For example:
<PermissionSet class=”System.Security.PermissionSet” version=”1”
ID=”Custom” SameSite=”site” Unrestricted=”true”/>
2. In the project file (with the .csproj or .vbproj extension),change
<TargetZone>Internet</TargetZone>
to
<TargetZone>Custom</TargetZone>
You can also make this change inside Visual Studio’s project properties UI on the
Security tab.

WPF unleashed, page 231