The mystery of the Windows 10 message box icons

I noticed that, in Columns UI, the Windows 10 standard error icon as displayed by MessageBox looks like this:

However, the error icon in my custom dialogue box looked like a bit of a relic in comparison:

I was left scratching my head. I was getting the icon by calling LoadImage and asking for the standard error icon (OIC_ERROR, also known as OIC_HAND, IDI_ERROR and IDI_HAND). Why would that return a different icon, and where does the mysterious version that MessageBox uses come from?

And, unsurprisingly, this problem wasn't just limited to the error icon. Here's a comparison of the various new and old MessageBox icons:

I looked at the resources in various Windows DLLs to try and find a clue to where the newer versions of the icons come from, thinking that perhaps they were different icons with different identifiers. However, I could only find various copies of the older Windows 7-era icons.

I then noticed that MessageBox only uses the newer icon when using a manifest specifying that Common Controls version 6 should be used. That suggested that the answer lay within the Common Controls, so I had a quick look on MSDN at what general Common Control functions existed. I soon found the LoadIconMetric and LoadIconWithScaleDown functions. Both of these return the newer icons when using version 6 of the Common Controls:

And that solves our mystery.^[1]

(Note, though, that these functions require the caller to destroy the returned icon when it's no longer needed, unlike LoadImage when used with the LR_SHARED flag.)