Provides a source to render the requested glyphs in the Glyphs element.
The Downloader object that contains either a zip file or a font file.
The string name identifying the font name in the zip file. This will be an empty string if the Downloader contains only one font file, or if you use the glyphTypeface signature.
The GlyphTypeface object that contains the font file. If you use this signature, always set part to empty string ("").
Passing a null value to the Downloader argument sets the Glyphs source to nothing, and does not render anything.
If a Downloader contains a file that is not a TrueType or OpenType font, an ArgumentException is raised along with the control's error event.