Mitigation: Pointer-based Touch and Stylus Support
WPF applications that target the .NET Framework 4.7 and are running on Windows starting with Windows 10 Creators Update can enable an optional WM_POINTER-based WPF touch/stylus stack.
Impact
Developers who do not explicitly enable pointer-based touch/stylus support should see no change in WPF touch/stylus behavior.
The following are current known issues with the optional WM_POINTER-based touch/stylus stack:
No support for real-time inking.
While inking and stylus plugins still work, they are processed on the UI thread, which can lead to poor performance.
Behavioral changes due to changes in promotion from touch/stylus events to mouse events.
Manipulation may behave differently.
Drag/Drop will not show appropriate feedback for touch input. (This does not affect stylus input.)
Drag/Drop can no longer be initiated on touch/stylus events.
This can potentially cause the application to become unresponsive until mouse input is detected. Instead, developers should initiate drag and drop from mouse events.
Opting in to WM_POINTER-based touch/stylus support
Developers who wish to enable this stack can add the following to their application's app.config file.
<configuration>
<runtime>
<AppContextSwitchOverrides value="Switch.System.Windows.Input.Stylus.EnablePointerSupport=true"/>
</runtime>
</configuration>
Removing this entry or setting its value to false turns this optional stack off.
