PLPperlblock should not be made 'transparent', because this incorrectly
preserves the current HTML highlight for default Perl code. Mixing Perl and
HTML styling can lead to very strange and unwanted effects, like partially
marking the following code as a comment:
<!-- <: print not_a_comment(); :> -->
syn cluster PLPperlcode contains=perlStatement.*,perlFunction,perlOperator,perlVarPlain,perlVarNotInMatches,perlShellCommand,perlFloat,perlNumber,perlStringUnexpanded,perlString,perlQQ,perlControl,perlConditional,perlRepeat,perlComment,perlPOD,perlHereDoc,perlPackageDecl,perlElseIfError,perlFiledescRead,perlMatch
syn cluster PLPperlcode contains=perlStatement.*,perlFunction,perlOperator,perlVarPlain,perlVarNotInMatches,perlShellCommand,perlFloat,perlNumber,perlStringUnexpanded,perlString,perlQQ,perlControl,perlConditional,perlRepeat,perlComment,perlPOD,perlHereDoc,perlPackageDecl,perlElseIfError,perlFiledescRead,perlMatch
-syn region PLPperlblock keepend matchgroup=Delimiter start=+<:=\=+ end=+:>+ transparent contains=@PLPperlcode
+syn region PLPperlblock keepend matchgroup=Delimiter start=+<:=\=+ end=+:>+ contains=@PLPperlcode
syn region PLPinclude keepend matchgroup=Delimiter start=+<(+ end=+)>+
syn region PLPinclude keepend matchgroup=Delimiter start=+<(+ end=+)>+