What Gray Blank Slots Mean in FontForge

In FontForge, encountering a blank slot with a gray background indicates that a character code exists in your current encoding mapping, but no glyph has been created or defined for it yet in the font file. This visual indicator helps designers immediately distinguish between characters that have not been drawn, characters that exist as invisible whitespace, and completed glyphs.

The Indicator Explained

The Font View window in FontForge organizes characters into a grid based on your chosen encoding standard, such as Unicode or ISO 8859-1. When you see a gray, empty slot:

  • Non-Existent Glyph: The font does not contain data or metrics for that specific character. FontForge is merely showing you the potential slot where that character would reside according to the current encoding table.
  • Placeholder Status: It serves as a placeholder. If you generate an OpenType or TrueType font file without creating that glyph, the resulting file will simply omit that character mapping.

Gray Background vs. White Background

Understanding the distinction between gray and white slots is essential for managing your font's character set:

  • Gray and Blank: The glyph does not exist. It has zero data, no custom advance width, and no vector paths assigned in the font database.
  • White and Blank: The glyph does exist in the font, but it contains no visible outlines. This is standard for intentional whitespace characters—such as the space (uni0020) or non-breaking space (uni00A0)—which have an advance width but no drawn contours. If an ordinary letter slot is white and empty, it means the glyph was created or edited, but lacks vector shapes.

How to Work with Gray Slots

To activate and define a gray slot:

  1. Open the Glyph: Double-click the gray cell. FontForge will instantly create the glyph entry and open the Glyph Outline window.
  2. Background Change: Once opened or drawn in, returning to the Font View will show that the cell's background has changed from gray to white.
  3. Filtering Unused Slots: If the gray empty slots create too much visual clutter, navigate to Encoding in the top menu and select Compact. This collapses the grid to display only the defined (non-gray) glyphs currently present in your project.