Include font name in the preview window.

[twisp007]

When opening a font with fontpreview the window only has "sxiv" as the title. If multiple fonts are opened it becomes hard to keep track which fontpreview window shows which font.

So including the proper name of the font in the preview window might better user experience.

[sdushantha]

That would be a good idea, especially for viewing single font files when using the command fontpreview /path/to/font.otf.
Another option would be to show the font name at the bottom of the preview image in some small text.

I'll work on this when I get some time 👍