t = page:GetCMYKStroke()
page:GetCMYKStroke() returns the current value of the page's stroking color. page:GetCMYKStroke() is valid only when
the page's stroking color space is #HPDF_CS_DEVICE_CMYK.
This function returns a table with the following fields initialized:
CYMKAll fields contain values between 0 and 1.