Any tips on debugging focus issues in WPF?

Question

Specifically, I have a button that opens a non-modal child window. Something in the main window steals the focus away from the child window as it opens.

The fully general approach is to comment out parts of code until the problem goes away. I'm looking for faster methods.

Answer 1

I'm using Snoop to do this right now.

For starters, Snoop shows the current focused element and the current FocusScope in the status bar.

You can get it to show you all the GotFocus and LostFocus events:

1. Run your app.
2. Run Snoop.
3. Choose your app in the dropdown.
4. Click the binoculars ("Snoop") button.
5. On the right pane, click the Events tab.
6. Click to bring down the dropdown.
7. Scroll down to the Keyboard section and check GotKeyboardFocus, LostKeyboardFocus, and optionally the PreviewXXX events.
8. Now do what you need to do to manipulate focus and watch the Snoop window.

Similarly you can track the FocusManager events the same way.