[Beta]: Mouse drag no longer creates a block selection in the Plate Playground

Bug type

Regression (worked before, now fails)

Browser surface

Yes

Summary

Dragging across multiple blocks in the Plate Playground creates a normal text selection instead of a visual block selection.

Public reproduction URL

https://platejs.org/

Steps to reproduce

1. Open the Plate Playground on the current next/Beta lane.
2. Start a mouse drag from the block-selection area beside the first heading.
3. Drag downward across the heading and following content blocks.
4. Release the pointer.

Expected behavior

The crossed blocks should be selected as whole blocks and display the block-selection rectangle. The Block Selection documentation explicitly supports multi-block selection using mouse drag.

Actual behavior

The editor creates a normal blue text selection across characters and displays the floating text toolbar. No block-selection rectangle or whole-block selection appears.

Acceptance criteria

• Mouse dragging from the block-selection area selects every crossed selectable block.
• Selected blocks display the block-selection visual indicator.
• The gesture does not fall back to a normal character-level text selection.

Plate / Slate / React versions

plate: NOT_ENOUGH_INFO
slate: NOT_ENOUGH_INFO
slate-react: NOT_ENOUGH_INFO
react: NOT_ENOUGH_INFO

Operating system

macOS (version NOT_ENOUGH_INFO)

Install method

Hosted Plate Playground

Framework / app setup

platejs.org Plate Playground

Affected packages or entry points

@platejs/selection, BlockSelectionPlugin, and the Plate Playground integration

Minimal code or config excerpt

NOT_ENOUGH_INFO

Logs, screenshots, and evidence

Recording timestamps:
[00:00–00:03] The pointer drags downward across the heading and following blocks.
[00:03–00:06] Characters are highlighted in blue and the floating text toolbar appears.
No block-selection rectangle is visible at any point.

Impact and severity

Affected: users relying on mouse-based multi-block selection in the current Plate Beta Playground. Severity: High; the primary mouse interaction for selecting multiple blocks is unavailable. Frequency: one captured attempt; broader frequency is NOT_ENOUGH_INFO. Consequence: block-level copy, cut, delete, and manipulation workflows cannot begin through mouse selection.

Additional information

Reference: https://platejs.org/docs/block-selection

Regression range:

• last-known-good: NOT_ENOUGH_INFO
• first-known-bad: Plate next/Beta observed 2026-08-06
• evidence: attached 6-second recording

The recording is from Plate next/Beta testing. No console error is visible. Exact browser and build identifiers are NOT_ENOUGH_INFO.

Video evidence:

https://github.com/user-attachments/assets/3f6723ab-f7a2-4baf-853f-f39e3bc53bed