Gets the currently-selected font.
Note that this can be a different string than what you set with set_font, as the font chooser widget may normalize font names and thus return a string with a different structure. For example, “Helvetica Italic Bold 12” could be normalized to “Helvetica Bold Italic 12”.
Use equal if you want to compare two font descriptions.
A FontDescription for the current font, or null if no font is selected.