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Gets or sets the color of the interior pattern as an index into the current color palette.
Use this property to read the palette-based color index applied to the current interior pattern. The returned value can also be a special value from ColorDataIndex, such as Automatic or None.
int PatternColorIndex { get; set; }
Property PatternColorIndex As Integer
IInterior interior = worksheet.Range["A1"].Interior;
interior.Pattern = Pattern.Solid;
interior.PatternColorIndex = 10;
int patternColorIndex = interior.PatternColorIndex;