src/vs/editor/common/cursor/cursorColumnSelection.ts/ColumnSelection/columnSelectLeft
class ColumnSelection:	public static columnSelectLeft(config: CursorConfiguration, model: ICursorSimpleModel, prevColumnSelectData: IColumnSelectData): IColumnSelectResult {
		let toViewVisualColumn = prevColumnSelectData.toViewVisualColumn;
		if (toViewVisualColumn > 0) {
			toViewVisualColumn--;
		}

		return ColumnSelection.columnSelect(config, model, prevColumnSelectData.fromViewLineNumber, prevColumnSelectData.fromViewVisualColumn, prevColumnSelectData.toViewLineNumber, toViewVisualColumn);
	}