Accepted Improve the Window for HP Optional Challenges

Issue
The current window for viewing and selecting optional challenges is difficult to use.
It's already problematic with two Tiers available, it will only be worse with ten Tiers in the future.

Spoiler: CASE #1

You have just completed Tier 1 and Rosa tells you that a new Tier is available.
You'd like to see what the new optional challenges are so what do you do?

- Type @challenges
- Click "Next" on the Story Quest and Class Quest window
- Select a category
- View all of the available challenges in that category
- Pick a new challenge or simply click "OK"
- The window closes

There are 8 categories so it's quite likely to have to repeat all of these steps 8 times.
After several repetitions, a warning appears to not repeat @challenges over and over.

Spoiler: CASE #2

You are interested in completing all of the optional challenges.
You'd like to find the outstanding challenges so what do you do?

- Type @challenges
- Click "Next" on the Story Quest and Class Quest window
- View the latest active challenge in each category

The completed active challenge is unremovable if there are no remaining challenges to take. You cannot easily distinguish between 1) you haven't picked another challenge yet, or 2) you could not select a new active challenge because there are no remaining challenges to take. You end up double-checking every category time and time again.

Suggestions

Spoiler: 1) Add a back button.

The main issue is that navigation is one-directional. Simply adding a back button would resolve most of the issues of having to constantly re-open the window to view different categories.

Spoiler: 2) After selecting a new active challenge, the 'OK' button does not close the window anymore.

The window should return to the screen with all of the current active challenges so that users can select other categories if they wish to.

Spoiler: 3) Add an option to select no active challenge for a category.

This fixes Case #2. It's easy to know if there are no remaining challenges to complete.

Spoiler: 4) Add a new window showing the optional challenges by Tier

This would be a cool historical record. It would also allow users to count how many optional challenges are completed for the current tier. In the present implementation, once another active challenge of any tier is selected for a particular category, the completed one disappears forever.