diff --git a/markdownhighlighter.cpp b/markdownhighlighter.cpp
index 9b3695f..d058666 100644
--- a/markdownhighlighter.cpp
+++ b/markdownhighlighter.cpp
@@ -522,6 +522,7 @@ void MarkdownHighlighter::setCurrentBlockMargin(
     blockFormat.setTopMargin(2);
     blockFormat.setBottomMargin(margin);
 
+    // TODO: this prevents "undo" in headlines
     QTextCursor* myCursor = new QTextCursor(currentBlock());
     myCursor->setBlockFormat(blockFormat);
 }