Backport WinFX changes to "v3.1" and "v5.0" SDKs #4253
Description
Can we backport WinFX changes from PRs (#2975, #2976, #4629, #4630) into v3.1 and v5.0 SDKs?
These changes (casing fix and double-import fix) shouldn't be high-risk change when all they do is fix some issues that were most common and frustrating to work around (at least in our case). I have checked with both patched SDKs from our side and v6.0 preview SDKs. They don't cause no major issues.
I already have the patches available targeting both v3.1 and v5.0 branches. It would be very helpful if the team could look this at priority. We thought we could wait until v6.0 releases but our build requires these two changes immediately. Having to apply the workaround on our CI while build is really a recipe for disaster.