Fix forbidden drag cursor feedback within editor tabs

[murataslan1]

Summary:

• update tab drag handlers to keep dropEffect in sync during drag enter/over
• set explicit move/copy/none effects for local editor/group drags in tab and editor drop targets
• keep unsupported-transfer behavior with dropEffect none

Notes:

• improves in-window drag cursor feedback (including tab reorder and merge paths)
• does not replace OS-level native cursor feedback outside the app window

Related: #199953
Fixes #245145

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@bpasero

Matched files:

• src/vs/workbench/browser/parts/editor/editorDropTarget.ts
• src/vs/workbench/browser/parts/editor/multiEditorTabsControl.ts

[bpasero]

I still see a red icon when attempting to drag an editor tab over the desktop on Windows, so this does not seem to help to fix the referenced issue?

[murataslan1]

Correct, this change is scoped to in-window tab/group drop targets and does not change OS-level cursor feedback when dragging over the desktop. I updated the PR scope to #245145 and kept #199953 as related context.

[benibenj]

Do you mind sharing a reproducible scenario which previously showed the incorrect drag marker and with this fix doesn't

[murataslan1]

@benibenj Sure — here is the repro scenario:

Steps to reproduce (before fix):

1. Open VS Code with multiple editor tabs
2. Drag a tab from one editor group and hover over a different editor group area (or within the same group to reorder)
3. While hovering over a valid drop target inside the editor area, the cursor briefly shows the "forbidden" (🚫) drag feedback before settling on the correct drop indicator

Expected (after fix):
The cursor shows the correct drop feedback immediately when hovering over valid in-window drop targets — no forbidden cursor flash.

I will record a before/after screen capture and attach it to this PR shortly.

[murataslan1]

Hi @benibenj — just checking in. I provided the repro scenario above on Feb 21. Let me know if you need any additional info or a screen recording to demonstrate the fix. Happy to help!