The readonly expression can be replaced and edited as a whole

[chenqianhe]

Description

The readonly expression can be replaced and edited as a whole

Steps to Reproduce

1. go to https://cortexjs.io/mathlive/guides/fill-in-the-blank/ and see the first readonly expression
2. select all by double-clicking
3. replace all contents directly by typing on the keyboard

2024-08-06_01-16-16.mp4

Actual Behavior

The readonly expression is replaced

Expected Behavior

Invalid operation

Environment

MathLive version not provided

macOS
Chrome Version 127.0.6533.89 (Official Build) (arm64)

[arnog]

Cleaned up comment above to make it more readable.