This is an update of [[Visual_Debugging|Visual Debugging]] page (focused on the old ConTeXt version [[Mark_II|Mark II]]) for the current [[Mark_IV|Mark IV]] and Mark XL (aka [[LMTX]]) versionsversion.
=Code=
=Visuals=
==Fonts==
<cmd>replacemissingcharacters</cmd> will replace characters missing in the font(s) with squares respecting font switches (<tt>\it</tt>, <tt>\bf</tt>). Underneath the squares are wanted characters, so though invisible, one can still search them or copy them to the editor to see the missing characters (in searchable PDF editors).