diff --git a/resources/desktop/com.github.rssguard.appdata.xml b/resources/desktop/com.github.rssguard.appdata.xml
index 3c5eb5c37..83f988c6b 100644
--- a/resources/desktop/com.github.rssguard.appdata.xml
+++ b/resources/desktop/com.github.rssguard.appdata.xml
@@ -26,7 +26,7 @@
   <url type="donation">https://github.com/sponsors/martinrotter</url>
   <content_rating type="oars-1.1" />
   <releases>
-    <release version="4.0.3" date="2021-10-05"/>
+    <release version="4.0.3" date="2021-10-08"/>
   </releases>
   <content_rating type="oars-1.0">
     <content_attribute id="violence-cartoon">none</content_attribute>
diff --git a/src/librssguard/core/messageobject.cpp b/src/librssguard/core/messageobject.cpp
index 8d9603c4c..e99bed915 100644
--- a/src/librssguard/core/messageobject.cpp
+++ b/src/librssguard/core/messageobject.cpp
@@ -3,6 +3,7 @@
 #include "core/messageobject.h"
 
 #include "3rd-party/boolinq/boolinq.h"
+#include "database/databasefactory.h"
 
 #include <QSqlDatabase>
 #include <QSqlError>
@@ -65,9 +66,8 @@ bool MessageObject::isDuplicateWithAttribute(MessageObject::DuplicationAttribute
   QString full_query = QSL("SELECT COUNT(*) FROM Messages WHERE ") + where_clauses.join(QSL(" AND ")) + QSL(";");
 
   qDebugNN << LOGSEC_MESSAGEMODEL
-           << "Query for MSG duplicate identification is: '"
-           << full_query
-           << "'.";
+           << "Prepared query for MSG duplicate identification is:"
+           << QUOTE_W_SPACE_DOT(full_query);
 
   q.setForwardOnly(true);
   q.prepare(full_query);
@@ -77,20 +77,23 @@ bool MessageObject::isDuplicateWithAttribute(MessageObject::DuplicationAttribute
   }
 
   if (q.exec() && q.next()) {
+    qDebugNN << LOGSEC_DB
+             << "Executed SQL for message duplicates check:"
+             << QUOTE_W_SPACE_DOT(DatabaseFactory::lastExecutedQuery(q));
+
     if (q.record().value(0).toInt() > 0) {
       // Whoops, we have the "same" message in database.
-      qDebugNN << LOGSEC_MESSAGEMODEL
-               << "Message '"
-               << title()
-               << "' was identified as duplicate by filter script.";
+      qDebugNN << LOGSEC_CORE
+               << "Message"
+               << QUOTE_W_SPACE(title())
+               << "was identified as duplicate by filter script.";
       return true;
     }
   }
   else if (q.lastError().isValid()) {
-    qWarningNN << LOGSEC_MESSAGEMODEL
-               << "Error when checking for duplicate messages via filtering system, error: '"
-               << q.lastError().text()
-               << "'.";
+    qWarningNN << LOGSEC_CORE
+               << "Error when checking for duplicate messages via filtering system, error:"
+               << QUOTE_W_SPACE_DOT(q.lastError().text());
   }
 
   return false;
diff --git a/src/librssguard/database/databasefactory.cpp b/src/librssguard/database/databasefactory.cpp
index 98bd56311..3e6ab929f 100644
--- a/src/librssguard/database/databasefactory.cpp
+++ b/src/librssguard/database/databasefactory.cpp
@@ -12,7 +12,9 @@
 #include "miscellaneous/textfactory.h"
 
 #include <QDir>
+#include <QSqlDriver>
 #include <QSqlError>
+#include <QSqlField>
 #include <QSqlQuery>
 #include <QVariant>
 
@@ -78,6 +80,25 @@ DatabaseDriver* DatabaseFactory::driverForType(DatabaseDriver::DriverType d) con
   });
 }
 
+QString DatabaseFactory::lastExecutedQuery(const QSqlQuery& query) {
+  QString str = query.lastQuery();
+  QMapIterator<QString, QVariant> it(query.boundValues());
+
+  while (it.hasNext()) {
+    it.next();
+
+    if (it.value().type() == QVariant::Type::Char ||
+        it.value().type() == QVariant::Type::String) {
+      str.replace(it.key(), QSL("'%1'").arg(it.value().toString()));
+    }
+    else {
+      str.replace(it.key(), it.value().toString());
+    }
+  }
+
+  return str;
+}
+
 QString DatabaseFactory::escapeQuery(const QString& query) {
   return QString(query)
          .replace(QSL("'"), QSL("''"));
diff --git a/src/librssguard/database/databasefactory.h b/src/librssguard/database/databasefactory.h
index 2c24c6bbe..726f50cf5 100644
--- a/src/librssguard/database/databasefactory.h
+++ b/src/librssguard/database/databasefactory.h
@@ -24,6 +24,7 @@ class DatabaseFactory : public QObject {
     DatabaseDriver* driver() const;
     DatabaseDriver* driverForType(DatabaseDriver::DriverType d) const;
 
+    static QString lastExecutedQuery(const QSqlQuery& query);
     static QString escapeQuery(const QString& query);
 
   private:
diff --git a/src/librssguard/gui/dialogs/formmain.cpp b/src/librssguard/gui/dialogs/formmain.cpp
index 5c1ff8131..43824495b 100644
--- a/src/librssguard/gui/dialogs/formmain.cpp
+++ b/src/librssguard/gui/dialogs/formmain.cpp
@@ -804,7 +804,9 @@ void FormMain::createConnections() {
   connect(m_ui->m_actionSelectPreviousMessage,
           &QAction::triggered, tabWidget()->feedMessageViewer()->messagesView(), &MessagesView::selectPreviousItem);
   connect(m_ui->m_actionSwitchMessageListOrientation, &QAction::triggered,
-          tabWidget()->feedMessageViewer(), &FeedMessageViewer::switchMessageSplitterOrientation);
+          tabWidget()->feedMessageViewer(), [this]() {
+    tabWidget()->feedMessageViewer()->switchMessageSplitterOrientation(true);
+  });
   connect(m_ui->m_actionShowOnlyUnreadItems, &QAction::toggled,
           tabWidget()->feedMessageViewer(), &FeedMessageViewer::toggleShowOnlyUnreadFeeds);
   connect(m_ui->m_actionShowTreeBranches, &QAction::toggled,
diff --git a/src/librssguard/gui/dialogs/formmessagefiltersmanager.cpp b/src/librssguard/gui/dialogs/formmessagefiltersmanager.cpp
index 3d0193a51..27908a3f3 100644
--- a/src/librssguard/gui/dialogs/formmessagefiltersmanager.cpp
+++ b/src/librssguard/gui/dialogs/formmessagefiltersmanager.cpp
@@ -596,6 +596,7 @@ Message FormMessageFiltersManager::testingMessage() const {
 
   msg.m_feedId = NO_PARENT_CATEGORY;
   msg.m_url = m_ui.m_txtSampleUrl->text();
+  msg.m_customId = m_ui.m_txtSampleUrl->text();
   msg.m_title = m_ui.m_txtSampleTitle->text();
   msg.m_author = m_ui.m_txtSampleAuthor->text();
   msg.m_isRead = m_ui.m_cbSampleRead->isChecked();
diff --git a/src/librssguard/gui/feedmessageviewer.cpp b/src/librssguard/gui/feedmessageviewer.cpp
index 5c7343fb7..70e78e450 100644
--- a/src/librssguard/gui/feedmessageviewer.cpp
+++ b/src/librssguard/gui/feedmessageviewer.cpp
@@ -2,6 +2,7 @@
 
 #include "gui/feedmessageviewer.h"
 
+#include "3rd-party/boolinq/boolinq.h"
 #include "core/feeddownloader.h"
 #include "core/feedsproxymodel.h"
 #include "core/messagesproxymodel.h"
@@ -23,6 +24,7 @@
 #include "miscellaneous/mutex.h"
 #include "miscellaneous/settings.h"
 #include "miscellaneous/systemfactory.h"
+#include "miscellaneous/templates.h"
 #include "services/standard/standardfeed.h"
 #include "services/standard/standardfeedsimportexportmodel.h"
 #include "services/standard/standardserviceroot.h"
@@ -87,8 +89,19 @@ void FeedMessageViewer::saveSize() {
   m_feedsView->saveAllExpandStates();
 
   // Store offsets of splitters.
-  settings->setValue(GROUP(GUI), GUI::SplitterFeeds, QString(m_feedSplitter->saveState().toBase64()));
-  settings->setValue(GROUP(GUI), GUI::SplitterMessages, QString(m_messageSplitter->saveState().toBase64()));
+  settings->setValue(GROUP(GUI), GUI::SplitterFeeds, toVariant(m_feedSplitter->sizes()));
+
+  if (!settings->value(GROUP(GUI), SETTING(GUI::SplitterMessagesIsVertical)).toBool()) {
+    settings->setValue(GROUP(GUI),
+                       GUI::SplitterMessagesHorizontal,
+                       toVariant(m_messageSplitter->sizes()));
+  }
+  else {
+    settings->setValue(GROUP(GUI),
+                       GUI::SplitterMessagesVertical,
+                       toVariant(m_messageSplitter->sizes()));
+  }
+
   settings->setValue(GROUP(GUI), GUI::MessageViewState, QString(m_messagesView->saveHeaderState().toBase64()));
 
   // Store "visibility" of toolbars and list headers.
@@ -100,9 +113,19 @@ void FeedMessageViewer::loadSize() {
   const Settings* settings = qApp->settings();
 
   // Restore offsets of splitters.
-  m_feedSplitter->restoreState(QByteArray::fromBase64(settings->value(GROUP(GUI), SETTING(GUI::SplitterFeeds)).toString().toLocal8Bit()));
-  m_messageSplitter->restoreState(QByteArray::fromBase64(settings->value(GROUP(GUI),
-                                                                         SETTING(GUI::SplitterMessages)).toString().toLocal8Bit()));
+  m_feedSplitter->setSizes(toList<int>(settings->value(GROUP(GUI),
+                                                       SETTING(GUI::SplitterFeeds))));
+
+  if (!settings->value(GROUP(GUI), SETTING(GUI::SplitterMessagesIsVertical)).toBool()) {
+    switchMessageSplitterOrientation(false);
+    m_messageSplitter->setSizes(toList<int>(settings->value(GROUP(GUI),
+                                                            SETTING(GUI::SplitterMessagesHorizontal))));
+  }
+  else {
+    m_messageSplitter->setSizes(toList<int>(settings->value(GROUP(GUI),
+                                                            SETTING(GUI::SplitterMessagesVertical))));
+
+  }
 
   QString settings_msg_header = settings->value(GROUP(GUI), SETTING(GUI::MessageViewState)).toString();
 
@@ -125,13 +148,33 @@ bool FeedMessageViewer::areListHeadersEnabled() const {
   return m_listHeadersEnabled;
 }
 
-void FeedMessageViewer::switchMessageSplitterOrientation() {
+void FeedMessageViewer::switchMessageSplitterOrientation(bool save_settings) {
   if (m_messageSplitter->orientation() == Qt::Orientation::Vertical) {
+    if (save_settings) {
+      qApp->settings()->setValue(GROUP(GUI),
+                                 GUI::SplitterMessagesVertical,
+                                 toVariant(m_messageSplitter->sizes()));
+    }
+
     m_messageSplitter->setOrientation(Qt::Orientation::Horizontal);
+    m_messageSplitter->setSizes(toList<int>(qApp->settings()->value(GROUP(GUI),
+                                                                    SETTING(GUI::SplitterMessagesHorizontal))));
   }
   else {
+    if (save_settings) {
+      qApp->settings()->setValue(GROUP(GUI),
+                                 GUI::SplitterMessagesHorizontal,
+                                 toVariant(m_messageSplitter->sizes()));
+    }
+
     m_messageSplitter->setOrientation(Qt::Orientation::Vertical);
+    m_messageSplitter->setSizes(toList<int>(qApp->settings()->value(GROUP(GUI),
+                                                                    SETTING(GUI::SplitterMessagesVertical))));
   }
+
+  qApp->settings()->setValue(GROUP(GUI),
+                             GUI::SplitterMessagesIsVertical,
+                             m_messageSplitter->orientation() == Qt::Orientation::Vertical);
 }
 
 void FeedMessageViewer::setToolBarsEnabled(bool enable) {
diff --git a/src/librssguard/gui/feedmessageviewer.h b/src/librssguard/gui/feedmessageviewer.h
index 26caa3f84..2343ced02 100644
--- a/src/librssguard/gui/feedmessageviewer.h
+++ b/src/librssguard/gui/feedmessageviewer.h
@@ -51,7 +51,7 @@ class RSSGUARD_DLLSPEC FeedMessageViewer : public TabContent {
     void loadMessageViewerFonts();
 
     // Switches orientation horizontal/vertical.
-    void switchMessageSplitterOrientation();
+    void switchMessageSplitterOrientation(bool save_settings);
 
     // Enables/disables main toolbars or list headers.
     void setToolBarsEnabled(bool enable);
diff --git a/src/librssguard/miscellaneous/settings.cpp b/src/librssguard/miscellaneous/settings.cpp
index c89d59b00..798beb93d 100644
--- a/src/librssguard/miscellaneous/settings.cpp
+++ b/src/librssguard/miscellaneous/settings.cpp
@@ -135,10 +135,16 @@ DKEY GUI::MessageViewState = "msg_view_state";
 DVALUE(QString) GUI::MessageViewStateDef = QString();
 
 DKEY GUI::SplitterFeeds = "splitter_feeds";
-DVALUE(char*) GUI::SplitterFeedsDef = "";
+DVALUE(QList<QVariant>) GUI::SplitterFeedsDef = {};
 
-DKEY GUI::SplitterMessages = "splitter_messages";
-DVALUE(char*) GUI::SplitterMessagesDef = "";
+DKEY GUI::SplitterMessagesIsVertical = "splitter_messages_is_vertical";
+DVALUE(bool) GUI::SplitterMessagesIsVerticalDef = true;
+
+DKEY GUI::SplitterMessagesVertical = "splitter_messages_vertical";
+DVALUE(QList<QVariant>) GUI::SplitterMessagesVerticalDef = {};
+
+DKEY GUI::SplitterMessagesHorizontal = "splitter_messages_horizontal";
+DVALUE(QList<QVariant>) GUI::SplitterMessagesHorizontalDef = {};
 
 DKEY GUI::ToolbarStyle = "toolbar_style";
 DVALUE(Qt::ToolButtonStyle) GUI::ToolbarStyleDef = Qt::ToolButtonIconOnly;
diff --git a/src/librssguard/miscellaneous/settings.h b/src/librssguard/miscellaneous/settings.h
index 47b8670f2..30bf883db 100644
--- a/src/librssguard/miscellaneous/settings.h
+++ b/src/librssguard/miscellaneous/settings.h
@@ -157,10 +157,16 @@ namespace GUI {
   VALUE(QString) MessageViewStateDef;
 
   KEY SplitterFeeds;
-  VALUE(char*) SplitterFeedsDef;
+  VALUE(QList<QVariant>) SplitterFeedsDef;
 
-  KEY SplitterMessages;
-  VALUE(char*) SplitterMessagesDef;
+  KEY SplitterMessagesIsVertical;
+  VALUE(bool) SplitterMessagesIsVerticalDef;
+
+  KEY SplitterMessagesVertical;
+  VALUE(QList<QVariant>) SplitterMessagesVerticalDef;
+
+  KEY SplitterMessagesHorizontal;
+  VALUE(QList<QVariant>) SplitterMessagesHorizontalDef;
 
   KEY ToolbarStyle;
   VALUE(Qt::ToolButtonStyle) ToolbarStyleDef;
diff --git a/src/librssguard/miscellaneous/skinfactory.cpp b/src/librssguard/miscellaneous/skinfactory.cpp
index 96c4d3cc1..3fb863d98 100644
--- a/src/librssguard/miscellaneous/skinfactory.cpp
+++ b/src/librssguard/miscellaneous/skinfactory.cpp
@@ -156,7 +156,7 @@ Skin SkinFactory::skinInfo(const QString& skin_name, bool* ok) const {
         skin.m_layoutMarkupWrapper = skin.m_layoutMarkupWrapper.replace(QSL(SKIN_STYLE_PLACEHOLDER),
                                                                         QString::fromUtf8(custom_css));
       }
-      catch (const IOException& ex) {
+      catch (...) {
         qWarningNN << "Skin"
                    << QUOTE_W_SPACE(skin_name)
                    << "does not support separated custom CSS.";
diff --git a/src/librssguard/miscellaneous/templates.h b/src/librssguard/miscellaneous/templates.h
index 323dc9d15..406adb53a 100644
--- a/src/librssguard/miscellaneous/templates.h
+++ b/src/librssguard/miscellaneous/templates.h
@@ -1,4 +1,28 @@
+// For license of this file, see <project-root-folder>/LICENSE.md.
+
 #ifndef TEMPLATES_H
 #define TEMPLATES_H
 
+#include <QVariantList>
+
+template <class T> static QVariant toVariant(const QList<T>& list) {
+  QVariantList variant_list; variant_list.reserve(list.size());
+
+  for (const auto& v : list) {
+    variant_list.append(v);
+  }
+
+  return variant_list;
+}
+
+template <class T> static QList<T> toList(const QVariant& qv) {
+  QList <T> data_list;
+
+  foreach(QVariant v, qv.value<QVariantList>()) {
+    data_list << v.value<T>();
+  }
+
+  return data_list;
+}
+
 #endif // TEMPLATES_H