Sets the spacing between lines of text in units of pixels. This setting will be used in all subsequent calls to the
Ptext function. Note, however, that the leading is reset by
PtextSize. For example, if the leading is set to 20 with
20 PtextLeading, then if
48 PtextSize is run at a later point, the leading will be reset to the default for the text size of 48.