Change Method Signature: parameter Type field doesn't visibly render typed text (contenteditable text node escapes shadow DOM slot)

[benanavd]

Environment

• OS: Windows 10/11 x64
• VS Code version: not captured
• Java extension version: 1.55.2026052308 (redhat.java)
• JDK: not captured

Steps to reproduce

1. Trigger Change Method Signature on any method.
2. Click the Type cell of a parameter and type a new type.

Result

The typed text does not appear in the Type field - the cell looks blank or unchanged.

Inspecting the DOM shows the text is captured, but as a direct text node on the <vscode-data-grid-cell contenteditable="true"> host, sitting outside the shadow root, which contains only:

<template shadowrootmode="open"><slot></slot></template>

The text is therefore present in the DOM but not visibly rendered. Example captured DOM:

<vscode-data-grid-cell ... contenteditable="true">.</template>Stringdjdajljdlrfajedfla</vscode-data-grid-cell>

where String is the original type and the rest is typed input.

Expected

Typed text should be visible in the Type cell while editing.

Note

vscode-data-grid-cell is from the deprecated Webview UI Toolkit; the contenteditable text node is not being placed into a slotted/rendered position.

[benanavd]

Adding the environment details that were missing from the original report, plus a tightened reproduction:

Environment

• OS: Windows 11 x64 (build 26200)
• VS Code version: 1.122.1 (user setup), commit 8761a5560cfd65fdd19ce7e2bd18dab5c0a4d84e, Chromium 142.0.7444.265, Electron 39.8.8
• Java extension version: 1.55.2026052308 (redhat.java)
• JDK: 21 (JavaSE-21)

Steps to reproduce (any project, any method)

1. Place the cursor on a method name, trigger the refactor, and choose Change Method Signature.
2. In the dialog, click the Type cell of an existing parameter to edit it.
3. Type any text (e.g. a new type name).

Result

• The typed text never appears in the cell — it looks blank/unchanged while editing.
• On clicking OK, the typed text is committed but appended to the original type rather than replacing it.

Root cause (confirmed via DOM inspection)
The edited text is captured as a bare text node placed directly on the contenteditable <vscode-data-grid-cell> host, outside its shadow root. The shadow root template is only:

<template shadowrootmode="open"><slot></slot></template>

so the text node is never assigned to a slotted/rendered position. It exists in the DOM but is never painted, which explains both the invisible-while-typing behavior and the append-on-commit behavior (new text node concatenated after the original type still on the host). Example captured DOM:

<vscode-data-grid-cell ... contenteditable="true">.</template>Stringdjdajljdlrfajedfla</vscode-data-grid-cell>

(String = original type, rest = typed input.)

vscode-data-grid-cell comes from the deprecated/archived Webview UI Toolkit, so this likely needs the dialog migrated off that component rather than a point fix.

Happy to attach a short screen recording of the empty field + append-on-OK if that helps reproduction.

[benanavd]

Confirmed: reproduces identically when launched with --disable-gpu, so this is not GPU/compositing-related — consistent with the contenteditable text node escaping the shadow-DOM slot rather than a rendering-layer problem.

[wenytang-ms]

working on #4449