Completion broken in read-only editors

[stevemessick]

Before the editor on a core library class became read-only it was possible to invoke code completion to see what other methods and types were available at any given site. That's no longer possible. It's important for those who want to learn the APIs.

Read-only editors should not ignore keyboard input. They should disallow modification but still respond to keyboard input. (I'm not entirely sure what the problem is because F3 still works for Open Declaration.)

[danrubel]

Removed Type-Defect label.
Added Type-Enhancement label.

[stevemessick]

Set owner to @stevemessick.
Added this to the M1 milestone.

[danrubel]

Removed this from the M1 milestone.
Added this to the Later milestone.

[DartBot]

This comment was originally written by [email protected]

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Added Editor-Usability label.

[stevemessick]

Added NotPlanned label.

[clayberg]

Removed this from the Later milestone.
Added this to the M5 milestone.