Instead of using a custom parse function to process {}, treat it as a

set of statements and parse with yacc, then convert back to a string as
the last step. This means the rules are consistent inside and outside
{}, %if and friends work at the right time, and the final result isn't
littered with unnecessary newlines.

tmux.1

@@ -552,17 +552,14 @@ is removed) and are not treated as having any special meaning - so for example
 variable.
 .El
 .Pp
-Braces are similar to single quotes in that the text inside is taken literally
-without any replacements but this also includes line continuation.
-Braces can span multiple lines in which case a literal newline is included in the
-string.
-They are designed to avoid the need for additional escaping when passing a group
-of
+Braces are parsed as a configuration file (so conditions such as
+.Ql %if
+are processed) and then converted into a string.
+They are designed to avoid the need for additional escaping when passing a
+group of
 .Nm
-or shell commands as an argument (for example to
-.Ic if-shell
-or
-.Ic pipe-pane ) .
+commands as an argument (for example to
+.Ic if-shell ) .
 These two examples produce an identical command - note that no escaping is
 needed when using {}:
 .Bd -literal -offset indent
@@ -570,7 +567,7 @@ if-shell true {
     display -p 'brace-dollar-foo: }$foo'
 }
 
-if-shell true "\en    display -p 'brace-dollar-foo: }\e$foo'\en"
+if-shell true "display -p 'brace-dollar-foo: }\e$foo'"
 .Ed
 .Pp
 Braces may be enclosed inside braces, for example: