This function allows you to calculate which Unicode characters in the current document have undefined glyphs in the currently selected font. Undefined glyphs are usually displayed as a square box or a square box with a question mark inside. You may launch this function by selecting "List Undefined Glyphs" from the Tools menu, or by pressing the sixth button on the Document toolbar. This option is only enabled if a single font is selected for the current document ("Single Font" checked under the Fonts menu); in composite font mode the menu item and the toolbar button will be disabled.
After the operation has completed a dialog box is displayed which either indicates that the current font has no undefined glyphs for characters in the current document, or indicates the number of characters with undefined glyphs that have been found (the number reported is the number of individual Unicode characters in the document that are not supported in the font, not the total number of occurences of characters with undefined glyphs).
The image below shows BabelPad with some Chinese text displayed using a single font (BabelStone Han). Three undefined glyphs (square boxes with question mark inside) are present, one on the first line, and two on the second line.
When the "List Undefined Glyphs" function is run by clicking on the List Undefined Glyphs button on the toolbar (a red question mark in a dashed square), the following results are reported:
The list of characters with undefined glyphs for this document/font combination can now be pasted into BabelPad, and it turns out that the BabelStone Han font does not have glyphs for the two characters U+2991B (occurs twice ) and U+2736A (occurs once).
