SpanWise on a 34-inch ultrawide
The wide profile starts with 40/60, Thirds, 30/40/30 and 4×2. Fill operations can cap overly wide windows at 1440 points and centre them inside the available region.
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Drag a divider, split a cell again, or type an exact ratio.
Keep several grids and switch the active one from the minimize-button palette. A 4 × 2 grid is useful for monitoring dashboards; 30/40/30 keeps a primary app centred between communication and reference tools.