TextBox overlay placed over Excel cell doesn't receive TextChanged events — Excel captures keystrokes (VSTO)

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TextBox overlay placed over Excel cell doesn't receive TextChanged events — Excel captures keystrokes (VSTO)

Mansour_Dalir 2,036

hi
I created a VSTO add-in that displays a WPF TextBox overlay positioned exactly over the currently selected Excel cell so users can edit inline. The overlay is visible and aligned correctly, but when I type, Excel captures all keystrokes and the TextBox does not receive TextChanged or KeyDown events.

VSTO TextChange_Event.txt

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Answer 3

Gade Harika (INFOSYS LIMITED) 1,870 Microsoft External Staff

Thanks for reaching out.
A WPF TextBox placed over the active Excel cell shows correctly, but typing goes to Excel. The TextBox never receives TextChanged or KeyDown.

you can use in a VSTO add‑in to make a WPF TextBox overlay over the active Excel cell receive KeyDown/TextChanged reliably. It addresses Excel’s focus‑stealing during selection changes and in‑cell edit mode.
1) WPF overlay window (top‑level, focusable)
please check below code
CellOverlayWindow.xaml.txt

2) VSTO wiring (subscribe, position, focus, commit/cancel)
please check below code
note 2 code.txt

3. What this solves (and why it works)

Excel steals focus on selection changes and when entering in‑cell edit.
The overlay is a top‑level, focusable WPF window. We defer Activate() + Focus() using Dispatcher.BeginInvoke (ApplicationIdle) so it executes after Excel’s own activation finishes.
We temporarily disable Application.EditDirectlyInCell while the overlay is shown, so Excel doesn’t switch to in‑cell edit and monopolize the input pipeline.
Optional Win32 focus (SetForegroundWindow + SetFocus) is available for stubborn environments.
Enter/Esc commit/cancel, then we restore focus to Excel and revert EditDirectlyInCell.

4) Usage notes

If you support IME/East Asian input, also wire PreviewTextInput and PreviewKeyDown on the TextBox.
Avoid AllowsTransparency=True/hit‑test transparent windows; they won’t own keyboard focus.
If your layout includes borders/margins, adjust overlay.Width/Height accordingly.

Let us know if the issue persists after following these steps. I’ll be happy to assist further if needed.

If the issue has been resolved, Kindly mark the provided solution as "Accept Answer", so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

Mansour_Dalir 2,036 Reputation points

2025-11-24T08:34:35.23+00:00

Hi

test no TextChangedEvent2.gif
The event doesn’t respond while typing; it only fires when clicking between filled or empty cells. My goal is for it to respond as I type so I can build a suggestion list, and when an item is found and Enter is pressed, the value should be inserted into the selected cell. Is such a process possible?
Gade Harika (INFOSYS LIMITED) 1,870 Reputation points Microsoft External Staff

2025-11-24T12:03:43.5066667+00:00
Excel owns keyboard focus and captures keystrokes, especially with EditDirectlyInCell enabled or after selection changes. To type directly into an overlay TextBox and receive TextChanged/KeyDown:

Use a top‑level, focusable WPF Window (not a child control/task pane) for the overlay.

Disable Application.EditDirectlyInCell while the overlay is active.

Defer Activate() + Focus() using Dispatcher.ApplicationIdle so you take focus after Excel finishes its activation.

Position the window using ActiveWindow.PointsToScreenPixelsX/Y for accurate zoom/scroll alignment.

On Enter, commit to ActiveCell.Value2 and close; on Esc, close without commit.

Hook TextChanged (and PreviewTextInput for IME) to update your suggestion list in real time.

This pattern reliably delivers live typing events for suggestion UIs. Sample code included above—drop it into your add‑in and adapt the commit/cancel logic to your needs.

One quick check

Are you currently hosting the TextBox inside a custom task pane or a top‑level window? If it’s in a pane/child control, moving to a top‑level window as shown above will resolve the focus/keystroke issue

If the issue has been resolved, Kindly mark the provided solution as "Accept Answer", so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.
Gade Harika (INFOSYS LIMITED) 1,870 Reputation points Microsoft External Staff

2025-11-27T12:46:11.24+00:00

Hope you're doing well. We're following up on this thread to check if the issue is still occurring or has been resolved. If it has been resolved, kindly mark the answer as accepted. We will close this thread by OCT 3rd.
Gade Harika (INFOSYS LIMITED) 1,870 Reputation points Microsoft External Staff

2025-12-01T11:56:48.82+00:00

Hope you're doing well. We're following up on this thread to check if the issue is still occurring or has been resolved. If it has been resolved, kindly mark the answer as accepted.
Gade Harika (INFOSYS LIMITED) 1,870 Reputation points Microsoft External Staff

2025-12-03T11:24:58.97+00:00

We haven’t received any further updates or follow-up on this case, so we’ll proceed with closing it at this time. If you require additional assistance or have new information to share, please feel free to raise new thread, we’re happy to support you further needed.

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TextBox overlay placed over Excel cell doesn't receive TextChanged events — Excel captures keystrokes (VSTO)

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