+  # Force presence of booleans for the useable_* flags.
+  my @useable_flags = qw(text_blocks sections);
+  $params->{"useable_for_${_}"} = !!$params->{"useable_for_${_}"} for @useable_flags;
+
+  # Force usage for text blocks if none of the check boxes are marked.
+  $params->{useable_for_text_blocks} = 1 if none { $params->{"useable_for_${_}"} } @useable_flags;
+