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+\usemodule[present-stepwise,present-bars,abr-01]
+
+\startdocument
+  [title=Visual debugging,
+   color=darkmagenta]
+
+\StartSteps
+
+\startsubject[title=How it started]
+
+    \startitemize[packed]
+
+        \startitem Some 15 years ago I wanted some more feedback. \stopitem \FlushStep
+        \startitem So I figured out a way to visualize boxes, kerns, glue, etc. \stopitem \FlushStep
+        \startitem Some aspects were tricky, like stretch and shrink (no \ETEX\ yet), fillers, leaders, etc. \stopitem \FlushStep
+        \startitem I gave some presentations and it was nice to see the puzzled faces. \stopitem \FlushStep
+        \startitem As unboxing does not work, it is somewhat interfering. \stopitem \FlushStep
+        \startitem When not enabed there is no overhead but we did disable it at some places. \stopitem \FlushStep
+
+    \stopitemize
+
+\stopsubject
+
+\startsubject[title=Do we need it]
+
+    \startitemize[packed]
+
+        \startitem I wonder if anyone ever used it. \stopitem \FlushStep
+        \startitem Some of the helpers are quite handy, like \type {\ruledhbox}. \stopitem \FlushStep
+        \startitem So these had to be provided anyway, so: where to stop? \stopitem \FlushStep
+
+    \stopitemize
+
+\stopsubject
+
+\StopSteps \page \StartSteps
+
+\startsubject[title=All kind of debugging]
+
+    \startitemize[packed]
+
+        \startitem We have more debugging, much shows up when writing new code. \stopitem \FlushStep
+        \startitem Think of fonts, math, graphics, characters, etc. \stopitem \FlushStep
+        \startitem Some make no sense in \MKIV, so they're gone, but new ones show up. \stopitem \FlushStep
+        \startitem In due time this will all be normalized (as most lives in modules). \stopitem \FlushStep
+
+    \stopitemize
+
+\stopsubject
+
+\StopSteps \page \StartSteps
+
+\startsubject[title=Why we kept it]
+
+    \startitemize[packed]
+
+        \startitem When cleaning up the code I had to decide to keep it or redo it as it could be done \MKIV-ish. \stopitem \FlushStep
+        \startitem But as we already had some \LUA\ based extras it made sense to redo it. \stopitem \FlushStep
+        \startitem The old code is still there as module (also because it had some more funstuff). \stopitem \FlushStep
+
+    \stopitemize
+
+\stopsubject
+
+\startsubject[title=How it worked]
+
+    \startitemize[packed]
+
+        \startitem In \MKII\ primitives are overloaded. \stopitem \FlushStep
+        \startitem So effectively, when enabled, \type {\hbox} cum suis become macros. \stopitem \FlushStep
+        \startitem We use rules (and leaders) to visualize properties. \stopitem \FlushStep
+        \startitem Some constructs interfere so we need to compensate side effects. \stopitem \FlushStep
+
+    \stopitemize
+
+\stopsubject
+
+\StopSteps \page \StartSteps
+
+\startsubject[title=How it works]
+
+    \startitemize[packed]
+
+        \startitem The basics were a rather trivial quick job as we had a lot in place already. \stopitem \FlushStep
+        \startitem Interpreting the node list and injecting visualizers. \stopitem \FlushStep
+        \startitem We use colors, rules and text but much can be overlayed. \stopitem \FlushStep
+        \startitem Control over what gets visualized at the \TEX\ end. \stopitem \FlushStep
+        \startitem Control over what gets shown by using layers. \stopitem \FlushStep
+        \startitem As usual most time went into visualization choices and optimzation. \stopitem \FlushStep
+        \startitem Some visualizers interfered with (hardcoded) expectations in the backend. \stopitem \FlushStep
+        \startitem When I decided to use layers I had to adapt some oter code (mostly out of efficiency). \stopitem \FlushStep
+        \startitem There is room for more (but first I want the bitlib of \LUA\ 5.2). \stopitem \FlushStep
+
+    \stopitemize
+
+\stopsubject
+
+\StopSteps
+
+\page
+
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+\startsubject[title=Details 1]
+
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+         {\getbuffer}\removeunwantedspaces
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+    \typebuffer
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+\ruledhbox{some depth too}
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