src/vs/workbench/browser/parts/views/viewPaneContainer.ts/ViewPaneContainer/computeInitialSizes
class ViewPaneContainer:	private computeInitialSizes(): Map<string, number> {
		const sizes: Map<string, number> = new Map<string, number>();
		if (this.dimension) {
			const totalWeight = this.viewContainerModel.visibleViewDescriptors.reduce((totalWeight, { weight }) => totalWeight + (weight || 20), 0);
			for (const viewDescriptor of this.viewContainerModel.visibleViewDescriptors) {
				if (this.orientation === Orientation.VERTICAL) {
					sizes.set(viewDescriptor.id, this.dimension.height * (viewDescriptor.weight || 20) / totalWeight);
				} else {
					sizes.set(viewDescriptor.id, this.dimension.width * (viewDescriptor.weight || 20) / totalWeight);
				}
			}
		}
		return sizes;
	}