Hatching in a region???

[kedaman]

If it's painting a region with the same color then floodfill api is for you

Private Declare Function FloodFill Lib "GDI32" (ByVal hDC As Long, ByVal X As Long, ByVal Y As Long, ByVal crColor As Long) As Long
'To use
FloodFill hDC, 100, 100, vbRed