diff -r dee5afe5301f -r 3f74d0d4af4c src/gui/itemviews/qstyleditemdelegate.cpp
--- a/src/gui/itemviews/qstyleditemdelegate.cpp	Mon Mar 15 12:43:09 2010 +0200
+++ b/src/gui/itemviews/qstyleditemdelegate.cpp	Thu Apr 08 14:19:33 2010 +0300
@@ -747,13 +747,8 @@
         return false;
     }
 
-    Qt::CheckState state;
-    if ( flags & Qt::ItemIsTristate ) {
-        state = static_cast<Qt::CheckState>( (value.toInt() + 1) % 3 );
-    } else {
-        state = (static_cast<Qt::CheckState>(value.toInt()) == Qt::Checked
+    Qt::CheckState state = (static_cast<Qt::CheckState>(value.toInt()) == Qt::Checked
                             ? Qt::Unchecked : Qt::Checked);
-    }
     return model->setData(index, state, Qt::CheckStateRole);
 }