Can select multiple “color” radio buttons at once

Repro:

• Load graph plugin to a run with session runs, but do not select a
  session run.
• Click the label for the “Compute time” radio button, which should
  be greyed out
• Note that nothing appears to happen: the default “Structure” radio
  button is selected
• Select a session run

Expected behavior: the “Structure” option should continue to be
selected, and no other radio button should be selected.

Actual behavior: both “Structure” and “Compute time” are visibly
selected, and both have the aria-checked="true", checked, and
active attributes. The graph is actually rendered in “Structure” mode.

Reproduce the graph plugin flow with session runs, first without selecting a session run and then after selecting one. Inspect the radio-button state during that transition; done means only “Structure” remains selected, with matching checked, active, and aria-checked state, while the graph still renders in Structure mode.