Returns the current serial number of fontmap. The serial number is
initialized to an small number larger than zero when a new fontmap
is created and is increased whenever the fontmap is changed. It may
wrap, but will never have the value 0. Since it can wrap, never compare
it with "less than", always use "not equals".
The fontmap can only be changed using backend-specific API, like changing
fontmap resolution.
This can be used to automatically detect changes to a PangoFontMap, like
in PangoContext.
Since 1.32.4
Returns the current serial number of fontmap. The serial number is initialized to an small number larger than zero when a new fontmap is created and is increased whenever the fontmap is changed. It may wrap, but will never have the value 0. Since it can wrap, never compare it with "less than", always use "not equals". The fontmap can only be changed using backend-specific API, like changing fontmap resolution. This can be used to automatically detect changes to a PangoFontMap, like in PangoContext. Since 1.32.4