Question

The following events can be used, but, they must be attach for each element:

GotKeyboardFocus, LostKeyboardFocus

Is there a way in .NET WPF to globally detect if the focused element changed ? without having to add event listeners for all possible elements ?

Answer 1

You can hook to the tunneling preview events:

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Height="350" Width="525" 
    PreviewGotKeyboardFocus="Window_PreviewGotKeyboardFocus" 
    PreviewLostKeyboardFocus="Window_PreviewLostKeyboardFocus">
....

This way, as shown above, the window would be notified before all descendants when any of the descendants gets or loses the keyboard focus.

Read this for more information.