Checkered background in main viewport


### Discussed in https://github.com/GraphiteEditor/Graphite/discussions/3914

<div type='discussions-op-text'>

<sup>Originally posted by **ameuret** March 19, 2026</sup>
Hey everyone,

A traditional checkered background is used everywhere (layers, color swatches, etc.) except where it matters most, the main viewport area, "_artboard_". What am I missing ?</div>