Test Grid Selectors

## A grid with checkbox selectors, with select-all enabled (top checkbox, and Ctrl/Cmd+A)

Tests for resetting columns (should not cause errors):

## A grid with radio selectors

## A grid with checkbox selectors, with select-all disabled, blank label in selector column

## A grid, initially without a selector column

Tests for resetting columns (should not cause errors, and selectors should work):

## A grid with checkbox selectors and column sets