Menu name maximum length limit and escape string

Menu name containing variables may have a large length, like `<menu name="${env.Path}">`.
Need to add a maximum length attribute to the menu element, like this:
```xml
<menu name="${env.Path}" max_length="16">
```

I tried some way, and couldn't display the string like "${env.Path}" in the Explorer menu, maybe the source code did not add support for escaping