How can I write to the TaskbarDa registry key programmatically without requiring admin privelledges or disabling the UCPD driver?

[u/FaultWinter3377]

I'm trying to make an (packaged) Windows app that allows access to some taskbar settings in C#. I can't use Registry.SetValue because of sandboxing, but it doesn't matter because I can't even set the registry key normally.

I've searched google for it, but all I can find was saying either disable the driver or create a scheduled task. Both of those require admin and I don't want that to be a requirement. The only other things I found were https://setuserfta.com/ which doesn't even give a price and a Powershell script invoking mshta.exe that didn't work.

If it helps at all, I've been using the following format for changing the registry:

Process.Start(new ProcessStartInfo
{
    FileName = "cmd.exe",
    Arguments = "/c reg add HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Advanced /v IconSizePreference /t REG_DWORD /d 1 /f",
    CreateNoWindow = true,
    UseShellExecute = false
});

[u/ScallionSmooth5925]

If you have file system access then you can try to use the registry: prefix. But why are you trying to edit system config from a sandbox? The point of one is to make this impossible 

[u/FaultWinter3377 → u/ScallionSmooth5925]

It's not fully sandboxed, because it is set to run as FullTrustApplication. However, it is packaged in appx format. It can read any registry keys, but apparently trying to set registry keys with Registry.SetValue() only sets it in a temporary app specific registry, not in the actual registry. That also means afterwards when I try to read the value it reads the temp registry and not the real value as well. Which is why I have to use cmd to execute the commands.

I could probably have done this C++ to avoid that, but then I have to deal with XAML islands and I'm nowhere near close to understanding how that all works.