2018-10-19

UseLegacyAccessibilityFeatures

Desktop applications are required to opt in to all earlier accessibility improvements to get the later imporvements. To do this, ensure that if the AppContext switch 'Switch.UseLegacyAccessibilityFeatures.N' and all 'Switche.UseLegacyAccessibilityFeatures.M' switches, when M<N, evaluate to false as well. Note that , if a switch for a particular set of accessibility improvements is not present, its value is determined by the target framework version. You can remedy this by adding these switches and setting their value to false.

桌面應用程序需要選擇加入所有早期的可訪問性改進，以獲得後期的改進。 為此，請確保如果AppContext切換'Switch.UseLegacyAccessibilityFeatures.N'和所有'Switche.UseLegacyAccessibilityFeatures.M'切換，當M <N時，也會評估為false。 請注意，如果不存在特定可訪問性改進集的交換機，則其值由目標框架版本確定。 您可以通過添加這些開關並將其值設置為false來解決此問題。

ref:
https://stackoverflow.com/questions/50417999/how-to-opt-in-to-accessibility-improvements
https://blogs.msdn.microsoft.com/dotnet/2017/09/21/net-framework-4-7-1-accessibility-and-wpf-improvements/


According to the blog post, .NET Framework 4.7.1 Accessibility and WPF Improvements , you need to add the following to your config file.
<runtime>
    <!-- AppContextSwitchOverrides value attribute is in the form of 'key1=true|false;key2=true|false  -->
    <AppContextSwitchOverrides value="Switch.UseLegacyAccessibilityFeatures=false" />
</runtime>