--- a/src/filterwidget.cpp	Thu Jun 18 19:35:22 2015 +0200
+++ b/src/filterwidget.cpp	Fri Jun 19 14:26:16 2015 +0200
@@ -15,14 +15,14 @@
 #include <QLineEdit>
 #include <QDebug>
 
-FilterWidget::FilterWidget(QSortFilterProxyModel *model, QWidget *parent, Qt::WindowFlags f) :
+FilterWidget::FilterWidget(QSortFilterProxyModel *model, bool addWithEmptyChk, 
+                           QWidget *parent, Qt::WindowFlags f) :
     QWidget(parent, f),
-    mModel(model) {
+    mModel(model),
+    mWithEmptyChk(addWithEmptyChk) {
     Q_ASSERT(model);
     setupGUI();
 
-    connect(mModel, &QSortFilterProxyModel::sourceModelChanged,
-            this, &FilterWidget::headersChanged);
     void (QComboBox:: *idxChanged)(int) = &QComboBox::currentIndexChanged;
     connect(mCombo, idxChanged, this,
             &FilterWidget::filterChanged);
@@ -32,6 +32,7 @@
 }
 
 void FilterWidget::headersChanged() {
+    mCombo->blockSignals(true);
     QAbstractItemModel *newSource = mModel->sourceModel();
     Q_ASSERT(newSource);
     mCombo->clear();
@@ -48,6 +49,7 @@
             }
         }
     }
+    mCombo->blockSignals(false);
 }
 
 void FilterWidget::filterChanged() {
@@ -74,6 +76,12 @@
     mEditLine->setClearButtonEnabled(true);
     baseLayout->addWidget(mEditLine);
 
+    if (mWithEmptyChk) {
+        mEmptyChk = new QCheckBox(tr("Include empty fields"));
+        baseLayout->addWidget(mEmptyChk);
+        connect(mEmptyChk, &QCheckBox::stateChanged, this, &FilterWidget::includeEmptyChanged);
+    }
+
     setLayout(root);
 }