Layout suggestions

- [ ] The toggle to turn the session on and off is lost unless in a horizontal layout. This should be easy to find, and available all the time.
- [ ] How to turn the input off should be more obvious. I want to stop taking input for a question, and not take input on another question until I choose to open it. In the busyness of a classroom, its not obvious how to do this.
- [ ] Numeric input should validate that it is numeric, and the histogram summary should allow scales/limits.
- [ ] I can easily see how to show the class just the results or the input without showing all the interface.

Start by running the application and tracing the session toggle, input controls, numeric input, histogram summary, and class display interface described in the issue. Separate the four suggestions into scoped changes and confirm the expected classroom workflow for each. Done means the session and input controls are always discoverable, numeric input is validated, histogram scales or limits can be set, and results or input can be shown without the full interface.

Written by the indexing model from the issue text.