Windows 10 SDK Preview Build 17686 released.

MSIX Support

It’s finally here! You can now package your applicatiinsons as MSIX! These applications can be installed and run on any device with 17682 build or later.

To package your application with MSIX, use the MakeAppx tool. To install the application – just click on the MSIX file.


We’ve made some important changes to the C/C++ ETW code generation of mc.exe (Message Compiler):

The “-mof” parameter is deprecated. This parameter instructs MC.exe to generate ETW code that is compatible with Windows XP and earlier. Support for the “-mof” parameter will be removed in a future version of mc.exe.

As long as the “-mof” parameter is not used, the generated C/C++ header is now compatible with both kernel-mode and user-mode, regardless of whether “-km” or “-um” was specified on the command line. The header will use the _ETW_KM_ macro to automatically determine whether it is being compiled for kernel-mode or user-mode and will call the appropriate ETW APIs for each mode.

  • The only remaining difference between “-km” and “-um” is that the EventWrite[EventName] macros generated with “-km” have an Activity ID parameter while the EventWrite[EventName] macros generated with “-um” do not have an Activity ID parameter.

The EventWrite[EventName] macros now default to calling EventWriteTransfer (user mode) or EtwWriteTransfer (kernel mode). Previously, the EventWrite[EventName] macros defaulted to calling EventWrite (user mode) or EtwWrite (kernel mode).

  • The generated header now supports several customization macros. For example, you can set the MCGEN_EVENTWRITETRANSFER macro if you need the generated macros to call something other than EventWriteTransfer.
  • The manifest supports new attributes.
    • Event “name”: non-localized event name.
    • Event “attributes”: additional key-value metadata for an event such as filename, line number, component name, function name.
    • Event “tags”: 28-bit value with user-defined semantics (per-event).
    • Field “tags”: 28-bit value with user-defined semantics (per-field – can be applied to “data” or “struct” elements).
  • You can now define “provider traits” in the manifest (e.g. provider group). If provider traits are used in the manifest, the EventRegister[ProviderName] macro will automatically register them.
  • MC will now report an error if a localized message file is missing a string. (Previously MC would silently generate a corrupt message resource.)
  • MC can now generate Unicode (utf-8 or utf-16) output with the “-cp utf-8” or “-cp utf-16” parameters.

Known Issues

  • MSIX: MSIX is not currently supported by the App Certification Kit nor the Microsoft Store at this time.

API Spot Light:

Check out LauncherOptions.GroupingPreference.

namespace Windows.System {
  public sealed class FolderLauncherOptions : ILauncherViewOptions {
    ViewGrouping GroupingPreference { get; set; }
  public sealed class LauncherOptions : ILauncherViewOptions {
    ViewGrouping GroupingPreference { get; set; }

This release contains the new LauncherOptions.GroupingPreference property to assist your app in tailoring its behavior for Sets.

Read more about API Updates, Additions and Removals here.