Debug.

packages/Boxout.sty

@@ -23,17 +23,30 @@
 	vlines		= {0pt,boxoutBG},
 	vline{1,Z}	= {\boxoutrule,boxoutFG},
 }
+% \SetTblrOuter[tblrBoxout]{
+% 	expand+		= \l_Boxout_body_tl,
+% }
 
-\str_const:Nn \c_Boxout_colspec_str {{X[l,h]}}
+\tl_const:Nn \c_Boxout_innerspec_tl {colspec={X[l,h]}}
 \bool_const:Nn \c_Boxout_warning_bool {\c_false_bool}
 
+\tl_new:N \l_Boxout_title_tl
+
 \keys_define:nn{Boxout}{
-	colspec		.str_set_e:N= \l_Boxout_colspec_str,
-	colspec		.initial:e	= {\c_Boxout_colspec_str},
+	innerspec	.tl_set_e:N= \l_Boxout_innerspec_tl,
+	innerspec	.initial:e	= {\c_Boxout_innerspec_tl},
+	innerspec	.default:e	= {\c_Boxout_innerspec_tl},
 
 	warning		.bool_set:N	= \l_Boxout_warning_bool,
+	warning		.initial:e	= {false},
+	warning		.default:e	= {true},
 }
 
+% \NewExpandableDocumentCommand{\__Boxout_body:Nnn}{m +m +m}{
+% 	%\message{boxout~body~start}
+
+% }
+
 \NewDocumentEnvironment{Boxout}{
 	% #1: Key-value options.
 	O{}
@@ -45,18 +58,23 @@
 	+b
 }{%
 	\keys_set:nn{Boxout}{#1}
-	\bool_if:nT \l_Boxout_warning_bool {%
-		\colorlet{boxoutBG}{warningBG}%
-		\colorlet{boxoutFG}{warningFG}%
-	}%
-	\label{box:#2}%
-	\message{colspec=\str_use:N \l_Boxout_colspec_str}
-	\SetTblrInner{colspec:e=\l_Boxout_colspec_str}
-	\begin{tblrBoxout}{}%
-		\IfBlankF{#3}{\Centering\sbfamily\bfseries #3\\}%
-		\setlength{\parskip}{\medskipamount}%
-		#4\\%
-	\end{tblrBoxout}%
+	\bool_if:nT \l_Boxout_warning_bool {
+		\colorlet{boxoutBG}{warningBG}
+		\colorlet{boxoutFG}{warningFG}
+	}
+	\label{box:#2}
+	\tl_if_empty:nTF {#3} {
+		\expanded{\noexpand\begin{tblrBoxout}{\l_Boxout_innerspec_tl}}
+			\setlength{\parskip}{\medskipamount}
+			#4\\
+		\end{tblrBoxout}
+	}{
+		\expanded{\noexpand\begin{tblrBoxout}{\l_Boxout_innerspec_tl}}
+			\SetCell{halign=c, font={\sbfamily\bfseries}}{#3}\\
+			\setlength{\parskip}{\medskipamount}
+			#4\\
+		\end{tblrBoxout}
+	}
 }{}
 
 \keys_define:nn{}{
@@ -69,8 +87,6 @@
 	O{}
 	% #2: Label, passed to Boxout argument #1.
 	>{\TrimSpaces}m
-		% #5: Tabularray colspec, passed to Boxout argument #2.
-		%O{X[l,h]}
 	% #3: Caption, passed to Boxout argument #3.
 	m
 	% #4: Body, passed to Boxout.
@@ -84,12 +100,12 @@
 		offset		= \l_BigFloat_offset_fp,
 	]%
 		\begin{Boxout}[%
-			warning=\l_Boxout_warning_bool,
-			colspec=\l_Boxout_colspec_str,
-		]{#2}[\l_Boxout_colspec_str]{#3}%
-			#4%
-		\end{Boxout}%
-	\end{BigFloat}%
+			innerspec:e	= \l_Boxout_innerspec_tl,
+			warning:e	= \bool_to_str:N \l_Boxout_warning_bool,
+		]{#2}{#3}
+			#4
+		\end{Boxout}
+	\end{BigFloat}
 }{}
 
 \str_const:Nn \c_WrapBoxout_position_str {o}
@@ -100,7 +116,7 @@
 	WrapBoxout	.inherit:n	= Boxout,
 }
 \keys_define:nn{WrapBoxout}{
-	position	.choices:nn	= {l,r,i,o}{
+	position	.choices:nn	= {L,l,R,r,I,i,O,o}{
 		\str_set:Nn \l_WrapBoxout_position_str {\l_keys_choice_tl}
 	},
 	position	.initial:e	= {\c_WrapBoxout_position_str},
@@ -126,8 +142,8 @@
 	\begin{wrapfigure}{\l_WrapBoxout_position_str}[\l_WrapBoxout_offset_dim]%
 		\begin{minipage}{\l_WrapBoxout_width_dim}%
 			\begin{Boxout}[
-				colspec	= \l_Boxout_colspec_str,
-				warning	= \l_Boxout_warning_bool,
+				innerspec:e	= \l_Boxout_innerspec_tl,
+				warning:e	= \bool_to_str:N \l_Boxout_warning_bool,
 			]{#2}{#3}%
 				#4%
 			\end{Boxout}%

packages/Floats.sty

@@ -19,6 +19,25 @@
 \floatstyle{plain}
 \newfloat{generic}{htpb}{lgf}
 
+% Function for converting clists generated by multichoice keys into strings.
+\NewDocumentCommand{\clist_use_default:Nnnn}{
+	% #1: Output string variable.
+	m
+	% #2: Input clist.
+	m
+	% #3: Default clist to use if #2 is empty.
+	m
+	% #4: Separator for \clist_use:Nn.
+	O{}
+}{
+	\clist_if_empty:NT #2 {
+		\clist_set:Ne #2 {#3}
+	}
+	\str_set:Ne #1 {
+		\clist_use:Nn #2 {#4}
+	}
+}
+
 % Maximum width adjustment to fit 2 16x9 screensots on one page.
 \dim_const:Nn \c_BigFloat_overhang_dim {0.54in}
 \str_const:Nn \c_BigFloat_type_str {generic}
@@ -57,10 +76,9 @@
 	+b
 }{%
 	\keys_set:nn{BigFloat}{#1}%
-	%\str_new:N \l_BigFloat_placement_str
-	\str_set:Ne \l_BigFloat_placement_str {
-		\clist_use:Nn \c_BigFloat_placement_clist {}
-	}
+	\clist_use_default:Nnnn \l_BigFloat_placement_str
+		{\l_BigFloat_placement_clist}
+		{\c_BigFloat_placement_clist}
 	\ExpEnvOption%
 	\begin{\l_BigFloat_type_str}[\l_BigFloat_placement_str]% float environment
 		\begin{SmartAdjustWidth}{%
@@ -88,11 +106,11 @@
 
 \clist_const:Nn \c_CenterFig_placement_clist {h, t, p, b}
 
-\str_new:N \l_CenterFig_placement_str
+\clist_new:N \l_CenterFig_placement_clist
 
 \keys_define:nn{CenterFig}{
 	placement	.multichoices:nn= {b,H,h,p,t}{
-		\str_put_right:Ne \l_CenterFig_placement_str {\l_keys_choice_tl}
+		\clist_put_right:Nn \l_CenterFig_placement_clist {\l_keys_choice_tl}
 	},
 }
 
@@ -109,11 +127,9 @@
 	m
 }{
 	\keys_set:nn{CenterFig}{#2}%
-	\str_if_empty:NT \l_CenterFig_placement_str {
-		\str_set:Ne \l_CenterFig_placement_str {
-			\clist_use:Nn \c_CenterFig_placement_clist {}
-		}
-	}
+	\clist_use_default:Nnnn \l_CenterFig_placement_str
+		{\l_CenterFig_placement_clist}
+		{\c_CenterFig_placement_clist}
 	\ExpEnvOption
 	\begin{figure}[\l_CenterFig_placement_str]%
 		\Centering%

packages/Header.sty

@@ -25,12 +25,12 @@
 \renewcommand{\headrulewidth}{0pt}
 \renewcommand{\footrulewidth}{0pt}
 
-\NewDocumentCommand{\chapappname}{}{Chapter \thechapter{}: }
-\NewDocumentCommand{\partlabel}{}{\partname{} \thepart{}: \parttitle}
+\NewDocumentCommand{\chapappname}{}{Chapter~\thechapter{}:~}
+\NewDocumentCommand{\partlabel}{}{\partname{}~\thepart{}:~\parttitle}
 
 \NewDocumentCommand{\Appendix}{}{
 	\appendix
-	\RenewDocumentCommand{\chapappname}{}{Appendix \thechapter{}: }
+	\RenewDocumentCommand{\chapappname}{}{Appendix~\thechapter{}:~}
 	\RenewDocumentCommand{\partlabel}{}{}
 }
 

packages/Layout.sty

@@ -62,7 +62,7 @@
 \ProvideLength{\contentwidth}[\textwidth + \marparwidth]
 
 \RequirePackage[
-	debug,
+	%debug,
 	balanced,
 	emergencystretch = 3em,
 	max-cost		= 25000,