Version 4.5 of Virtual Keyboard for WPF adds following new features and improvements -

Key improvements
~ the UnicodeKey class can send any Unicode symbol as input to target text controls;
~ the IsPressed property is set to true while a key is pressed down by the user, allowing for data triggers in Xaml templates to change appearance of pressed keys;
~ RegularKey.Content can now be sent to external processes;

Keyboard improvements
~ a new Windows10 color scheme added to MindFusion.UI.Wpf.ColorSchemes;
~ the SetKeyLabels(CultureInfo, KeyLabels[]) method lets you override labels of keys for a given language;
~ keyboard editor fixes;

Active window tracking
~ the control updates its layout immediately when a window with a different current language activates;
~ pressing a key no longer activates last target window, which was necessary when keyboard is used as a popup inside application but led to activation flickering; set the new PreventActivation property instead to disable the keyboard's popup window from activating altogether;

If anyone is interested in trying the beta version, please download this archive containing updated assembly and sample files:
https://mindfusion.eu/_beta/vkwpf45.zip

Any comments, questions and general feedback are welcome.