diff -r 7ff1984af2a2 kate/view/kateviewhelpers.cpp
--- a/kate/view/kateviewhelpers.cpp	Wed Mar 24 21:06:29 2010 -0300
+++ b/kate/view/kateviewhelpers.cpp	Wed Mar 24 21:07:31 2010 -0300
@@ -1432,6 +1432,9 @@
   QVector<int> vec( 33 );
   int i=1;
 
+  QActionGroup actionGroup(&selectDefaultMark);
+  actionGroup.setExclusive(true);
+
   for( uint bit = 0; bit < 32; bit++ ) {
     MarkInterface::MarkTypes markType = (MarkInterface::MarkTypes)(1<<bit);
     if( !(m_doc->editableMarks() & markType) )
@@ -1456,6 +1459,8 @@
     if( markType & KateViewConfig::global()->defaultMarkType() )
       dMA->setChecked(true );
 
+    actionGroup.addAction(dMA);
+
     vec[i++] = markType;
   }