TFillStyle in Delphi’s VCL Windows UI toolkit indicates the type of color change that defines the boundary of a possibly non-rectangular region on a canvas.
TFillStyle values determine what type of color changes define the boundaries of a (possibly) non-rectangular region of a canvas, as indicated in the following table:
| Value | Meaning |
| fsSurface | The region is defined as all areas that have a specified color. When another color is encountered, it is taken as the boundary of the region. |
| fsBorder | The region is defined as any area that does not have a specified color. When the specified color is encountered, it is taken as the boundary of the region. |
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