Disable all children of disabled node

[mellis481]

As a maintainer, I'm logging this "feature request" because it's something my team plans on executing in the foreseeable future, but I want there to be visibility to the consumers of this library. Please provide feedback if you have any regarding this issue.

Core Principles
There are two principles for a tree component that must be upheld with regard to parent nodes to ensure good usability and accessibility. A parent node should:

1. always correctly inform the checked status of its children.
2. provide a convenient means for selecting/unselected children.

Problem Statement
Being able to disable a parent node and have its children not also be disabled automatically creates situation that doesn't make any sense and creates usability and accessibility issues

Details
Currently, only nodes passed in defaultDisabledIds will be disabled. This means that if a parent is disabled, its children will not automatically be disabled. eg:

In the example above, it doesn't make any logical sense to say "'Tea' should not be selectable, but all of its children should be."

More importantly, being able to select children of a disabled parent creates serious issues due to propagating selection to/through the disabled parent node. Currently, no selection (not even half-selection) is propagated to/through a disabled parent node when a child is selected. This causes usability and accessibility issues when the parent (or grandparent) is collapsed because a user can't tell what children are selected. If you argue "well then just propagate selection to/through the disabled parent node", that would create a situation where you could effectively select a disabled node by selecting all of its children which would be a huge issue.

For these reasons, children of a disabled parent node should be automatically disabled.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue was closed automatically since it was marked as stale because it has not had recent activity. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue was closed automatically since it was marked as stale because it has not had recent activity. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue was closed automatically since it was marked as stale because it has not had recent activity. Thank you for your contributions.