cabana: fix rounding error in filter sizehint (#28116)

old-commit-hash: b3a3040d09

tools/cabana/messageswidget.cc

@@ -544,7 +544,7 @@ void MessageViewHeader::updateGeometries() {
 QSize MessageViewHeader::sizeHint() const {
   QSize sz = QHeaderView::sizeHint();
   if (editors[0]) {
-    sz.setHeight(sz.height() + editors[0]->minimumSizeHint().height());
+    sz.setHeight(sz.height() + editors[0]->minimumSizeHint().height() + 1);
   }
   return sz;
 }