Microsoft has locked the possibility to execut WinForms applications directly in Internet Explorer, i.e. IE Sourcing
"This is in fact a security restriction from .NET Framework 4.0 onwards, since it’s not really recommended to use .NET ActiveX controls in IE, specifically ones created with previous versions of the framework. If you need to continue using this control, you’ll need to create these registry keys (depending on the OS architecture) on all machines where the control is used."
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework]
"EnableIEHosting"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework]
"EnableIEHosting"=dword:00000001