diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4b86b887bf2..0fae18018b6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1742,10 +1742,10 @@ if(KEYFINDER)
     set(KeyFinder_INSTALL_DIR "${CMAKE_CURRENT_BINARY_DIR}/lib/keyfinder-install")
     set(KeyFinder_LIBRARY "lib/${CMAKE_STATIC_LIBRARY_PREFIX}keyfinder${CMAKE_STATIC_LIBRARY_SUFFIX}")
     file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/download")
-    ExternalProject_Add(libKeyFinder
-      URL "https://github.com/mixxxdj/libKeyFinder/archive/v2.2.3.zip"
-      URL_HASH SHA256=56887e7b51834223d4264f4ea9acf16f0b6a0c706c218478afbaf89ad1f9c6ea
-      DOWNLOAD_DIR "${CMAKE_CURRENT_BINARY_DIR}/download/libKeyFinder"
+    ExternalProject_Add(libkeyfinder
+      URL "https://github.com/mixxxdj/libkeyfinder/archive/v2.2.3.zip"
+      URL_HASH SHA256=ad43ca006e3bbed0810ff62e170d04522a64f8606c2166bfa5a9b9158b7ebc11
+      DOWNLOAD_DIR "${CMAKE_CURRENT_BINARY_DIR}/download/libkeyfinder"
       INSTALL_DIR "${KeyFinder_INSTALL_DIR}"
       CMAKE_ARGS
         -DBUILD_STATIC_LIBS=ON
@@ -1769,7 +1769,7 @@ if(KEYFINDER)
     file(MAKE_DIRECTORY "${KeyFinder_INSTALL_DIR}/include")
 
     add_library(mixxx-keyfinder STATIC IMPORTED)
-    add_dependencies(mixxx-keyfinder libKeyFinder)
+    add_dependencies(mixxx-keyfinder libkeyfinder)
     set_target_properties(mixxx-keyfinder PROPERTIES IMPORTED_LOCATION "${KeyFinder_INSTALL_DIR}/${KeyFinder_LIBRARY}")
     target_link_libraries(mixxx-keyfinder INTERFACE FFTW::FFTW)
     target_include_directories(mixxx-keyfinder INTERFACE "${KeyFinder_INSTALL_DIR}/include")
diff --git a/res/skins/LateNight/decks/preview_deck.xml b/res/skins/LateNight/decks/preview_deck.xml
index 719f1ab6c2b..d009b717f20 100644
--- a/res/skins/LateNight/decks/preview_deck.xml
+++ b/res/skins/LateNight/decks/preview_deck.xml
@@ -4,7 +4,7 @@
 
   <!-- This wrapper makes the PreviewDeck borders work correctly -->
   <WidgetGroup>
-    <Layout>vertical</Layout>
+    <Layout>horizontal</Layout>
     <SizePolicy>me,max</SizePolicy>
     <Children>
 
@@ -165,6 +165,12 @@
         </Children>
       </WidgetGroup><!-- PreviewDeck -->
 
+      <WidgetGroup>
+        <ObjectName>PreviewDeckRightSpacer</ObjectName>
+        <Layout>horizontal</Layout>
+        <Children/>
+      </WidgetGroup>
+
     </Children>
     <Connection>
       <ConfigKey>[PreviewDeck],show_previewdeck</ConfigKey>
diff --git a/res/skins/LateNight/library.xml b/res/skins/LateNight/library.xml
index 7311eff7908..6cb0e50ba98 100644
--- a/res/skins/LateNight/library.xml
+++ b/res/skins/LateNight/library.xml
@@ -28,6 +28,8 @@
                 <MinimumSize>100,</MinimumSize>
                 <Children>
 
+                  <Template src="skin:/decks/preview_deck.xml"/>
+
                   <!--Search Input Field + Library Expand toggle -->
                   <WidgetGroup>
                     <ObjectName></ObjectName>
@@ -69,7 +71,11 @@
                     </Children>
                   </WidgetGroup><!-- SearchLineBox -->
 
-                  <Template src="skin:/decks/preview_deck.xml"/>
+                  <WidgetGroup>
+                    <ObjectName>SearchTreeSpacer</ObjectName>
+                    <Layout>horizontal</Layout>
+                    <Children/>
+                  </WidgetGroup>
 
                   <Splitter>
                     <ObjectName>SidebarCoverSplitter</ObjectName>
diff --git a/res/skins/LateNight/palemoon/buttons/btn__lib_checkmark_grey.svg b/res/skins/LateNight/palemoon/buttons/btn__lib_checkmark_grey.svg
new file mode 100644
index 00000000000..8c1e80dac7c
--- /dev/null
+++ b/res/skins/LateNight/palemoon/buttons/btn__lib_checkmark_grey.svg
@@ -0,0 +1,3 @@
+<svg width="10" height="10" version="1.1" xmlns="http://www.w3.org/2000/svg">
+  <path d="m2.0001 6.0001 2 2 4-5.9999" fill="none" stroke="#666" stroke-linecap="round" stroke-linejoin="round" stroke-width="2"/>
+</svg>
diff --git a/res/skins/LateNight/palemoon/style/lib_bg.png b/res/skins/LateNight/palemoon/style/lib_bg.png
deleted file mode 100644
index 8d66380880c..00000000000
Binary files a/res/skins/LateNight/palemoon/style/lib_bg.png and /dev/null differ
diff --git a/res/skins/LateNight/style_classic.qss b/res/skins/LateNight/style_classic.qss
index 2f3465a1be6..00b528b1f6a 100644
--- a/res/skins/LateNight/style_classic.qss
+++ b/res/skins/LateNight/style_classic.qss
@@ -65,6 +65,7 @@ WLibrary,
 #SidebarBox,
 #PreviewDeck,
 #LibExpandBox,
+#LibrarySplitter::handle,
 #SearchLineBox {
   border-top: 1px solid #333;
   border-left: 1px solid #333;
@@ -126,6 +127,30 @@ WSearchLineEdit,
   background-color: #080808;
 }
 
+/* Some tweaks to create a frameless library table */
+#LibrarySplitter {
+  border-width: 0px;
+  }
+  #LibrarySplitter::handle {
+    border-width: 1px 0px 0px 0px;
+    border-top-right-radius: 0px;
+    border-bottom-right-radius: 0px;
+    border-bottom-left-radius: 0px;
+  }
+  #PreviewDeckRightSpacer,
+  #SearchTreeSpacer {
+    border-right: 1px solid #333;
+    background-color: transparent;
+    }
+    #PreviewDeckRightSpacer {
+      min-width: 4px;
+      max-width: 4px;
+    }
+    #SearchTreeSpacer {
+      min-height: 3px;
+      max-height: 3px;
+    }
+
 /* background of fillers */
 #FxRackFillerL,
 #FxRackFillerR,
@@ -225,10 +250,6 @@ WBeatSpinBox,
 
 WLibrary {
   border-top-left-radius: 0px;
-}
-WLibrary,
-#SearchLineBox {
-  border-top: 0px;
   }
   #SearchLineBox {
   padding-right: 2px;
@@ -239,9 +260,8 @@ WLibrary,
 
 #LibExpandBox {
   qproperty-layoutAlignment: 'AlignVCenter | AlignHCenter';
-  border-width: 0px 0px 1px 0px;
+  border-width: 1px 0px 1px 0px;
   border-radius: 0px;
-  margin-bottom: 3px;
   padding: 0px 0px 2px 2px;
 }
 
@@ -312,8 +332,6 @@ WLibrary,
 #FxRackFillerL,
 #MicAuxRack,
 #SamplerRow,
-#LibExpandBox,
-#SearchLineBox,
 #PreviewDeck {
   margin-bottom: 4px;
 }
@@ -354,10 +372,6 @@ WLibrary,
   qproperty-layoutSpacing: 3;
 }
 
-#PreviewDeck {
-  margin-right: 3px;
-}
-
 #SkinSettingsContainer {
   margin-left: 3px;
 }
@@ -942,7 +956,7 @@ WPushButton#FxSuperLinkInvertButton {
 
   #PreviewDeckTextBox {
     }
-    #PreviewLabel { /* Placeholder */
+    #PreviewLabel { /* Placeholder when no track is loaded */
       padding-left: 2px;
     }
     #PreviewTitle {
@@ -2278,13 +2292,7 @@ WSearchLineEdit {
 /* LibrarySplitter
   (the splitter itself is vertical)
   Used to split Library sidebar & Tracks table */
-#LibrarySplitter {
-  border-top: 1px solid #333333;
-}
-#LibrarySplitter::handle { /*
-  background-image: url(skin:/classic/style/library_splitter_handle_unchecked.svg);
-  background-position: center top;
-  background-repeat: no-repeat;  */
+#LibrarySplitter::handle {
   image: url(skin:/classic/style/splitter_handle_vertical.png);
   background-color: #1e1e1e;
 }
diff --git a/res/skins/LateNight/style_palemoon.qss b/res/skins/LateNight/style_palemoon.qss
index f6bc1e5a266..8decacb728b 100644
--- a/res/skins/LateNight/style_palemoon.qss
+++ b/res/skins/LateNight/style_palemoon.qss
@@ -75,9 +75,7 @@
 #PreviewDeck,
 #SidebarCoverSplitter,
 #SidebarCoverSplitter:handle,
-/*#LibrarySplitter,*/
 #LibrarySplitter::handle,
-/*WLibrary,*/
 QAbstractScrollArea::corner {
   border-top: 1px solid #212123;
   border-right: 1px solid #111;
@@ -92,10 +90,8 @@ QAbstractScrollArea::corner {
   }
 
   #SidebarSearchPreviewContainer {
-    background-color: #0f0f0f;
+    margin-top: 1px;
   }
-
-  /*WLibrary,*/
   #SidebarBox {
     padding: 2px 0px 0px 2px;
     }
@@ -105,7 +101,6 @@ QAbstractScrollArea::corner {
       border-bottom-left-radius: 0px;
       border-top-left-radius: 0px;
     }
-  /*WLibrary,*/
   #SidebarCoverSplitter,
   #SidebarCoverSplitter::handle,
   #LibrarySplitter,
@@ -116,6 +111,7 @@ QAbstractScrollArea::corner {
     #SidebarCoverSplitter::handle {
       border-width: 0px;
     }
+    /* Some tweaks to create a frameless library table */
     #LibrarySplitter {
       border-width: 0px;
       }
@@ -125,12 +121,20 @@ QAbstractScrollArea::corner {
     WLibrary {
       border-width: 1px 0px 0px 0px;
     }
-/* Some tweaks to create a frameless library table */
+    #PreviewDeckRightSpacer,
+    #SearchTreeSpacer {
+      border-right: 1px solid #222;
+      background-color: transparent;
+      }
+      #PreviewDeckRightSpacer {
+        min-width: 3px;
+        max-width: 3px;
+      }
+      #SearchTreeSpacer {
+        min-height: 3px;
+        max-height: 3px;
+      }
 #LibraryContainer {
-  background-color: #151517;
-  background-image: url(skin:/palemoon/style/lib_bg.png);
-  background-position: top;
-  background-repeat: repeat-x;
 }
   #LibraryContainer QScrollBar::handle:horizontal,
   #LibraryContainer QScrollBar::handle:vertical,
@@ -173,6 +177,7 @@ WSearchLineEdit {
     padding: 5px 0px 0px 8px;
     border-top: 1px solid #212123;
   }
+
   #WaveformsFrame,
   #OverviewBox,
   #OverviewBoxMini,
@@ -242,7 +247,6 @@ WSearchLineEdit {
 }
 
 #SearchLineBox {
-  margin-top: 1px;
   padding-right: 2px;
   border-right: 0px;
   border-top-right-radius: 0px;
@@ -254,9 +258,7 @@ WSearchLineEdit {
   border-right: 0px;
   border-left: 0px;
   border-radius: 0px;
-  margin-bottom: 3px;
   padding: 0px 2px 2px 2px;
-  margin-top: 1px;
 }
 
 #SidebarBox {
@@ -397,8 +399,6 @@ WSearchLineEdit {
 #FxRackFillerL,
 #MicAuxRack,
 #SamplerRow,
-#LibExpandBox,
-#SearchLineBox,
 #PreviewDeck {
   margin-bottom: 3px;
 }
@@ -445,7 +445,8 @@ WSearchLineEdit {
 }
 
 #PreviewDeck {
-  margin-right: 3px;
+  /* right margin is managed by #PreviewDeckRightSpacer which
+    also generates the left border of the splitter handle */
 }
 
 #SkinSettingsContainer {
@@ -1089,7 +1090,7 @@ WPushButton#FxSuperLinkInvertButton {
 
   #PreviewDeckTextBox {
     }
-    #PreviewLabel { /* Placeholder */
+    #PreviewLabel { /* Placeholder when no track is loaded */
       padding-left: 2px;
     }
     #PreviewTitle {
@@ -1233,10 +1234,18 @@ WEffectSelector,
   font-size: 14px;
 }
   /* dim² ivory */
-  #Deck1 #PlayPositionText, #DeckCompact1 #PlayPositionTextSmall, #DeckMini1 #PlayPositionTextSmall,
-  #Deck1 #KeyText,  #DeckCompact1 #KeyText, #DeckMini1 #KeyTextSmall,
-  #Deck2 #PlayPositionText, #DeckCompact2 #PlayPositionTextSmall, #DeckMini2 #PlayPositionTextSmall,
-  #Deck2 #KeyText,  #DeckCompact2 #KeyText, #DeckMini2 #KeyTextSmall,
+  #Deck1 #PlayPositionText,
+    #DeckCompact1 #PlayPositionTextSmall,
+    #DeckMini1 #PlayPositionTextSmall,
+    #Deck1 #KeyText,
+    #DeckCompact1 #KeyText,
+    #DeckMini1 #KeyTextSmall,
+  #Deck2 #PlayPositionText,
+    #DeckCompact2 #PlayPositionTextSmall,
+    #DeckMini2 #PlayPositionTextSmall,
+    #Deck2 #KeyText,
+    #DeckCompact2 #KeyText,
+    #DeckMini2 #KeyTextSmall,
   #SamplerBpm, #SamplerBpmMini,
   #LibraryContainer QHeaderView {
     color: #766b65;
@@ -1248,16 +1257,30 @@ WEffectSelector,
   }
 
 /* pale blue */
-#Deck3 #TitleText, #Deck3 #ArtistText,
-  #DeckCompact3 #TitleText, #DeckCompact3 #ArtistText,
-  #DeckMini3 #TitleTextSmall, #DeckMini3 #ArtistTextSmall,
-  #Deck3 #BpmText, #DeckCompact3 #BpmText, #DeckMini3 #BpmTextSmall,
-  #Deck3 #KeyText,  #DeckCompact3 #KeyText, #DeckMini3 #KeyTextSmall,
-#Deck4 #TitleText, #Deck4 #ArtistText,
-  #DeckCompact4 #TitleText, #DeckCompact4 #ArtistText,
-  #DeckMini4 #TitleTextSmall, #DeckMini4 #ArtistTextSmall,
-  #Deck4 #BpmText, #DeckCompact4 #BpmText, #DeckMini4 #BpmTextSmall,
-  #Deck4 #KeyText,  #DeckCompact4 #KeyText, #DeckMini4 #KeyTextSmall {
+#Deck3 #TitleText,
+  #Deck3 #ArtistText,
+  #DeckCompact3 #TitleText,
+  #DeckCompact3 #ArtistText,
+  #DeckMini3 #TitleTextSmall,
+  #DeckMini3 #ArtistTextSmall,
+  #Deck3 #BpmText,
+  #DeckCompact3 #BpmText,
+  #DeckMini3 #BpmTextSmall,
+  #Deck3 #KeyText,
+  #DeckCompact3 #KeyText,
+  #DeckMini3 #KeyTextSmall,
+#Deck4 #TitleText,
+  #Deck4 #ArtistText,
+  #DeckCompact4 #TitleText,
+  #DeckCompact4 #ArtistText,
+  #DeckMini4 #TitleTextSmall,
+  #DeckMini4 #ArtistTextSmall,
+  #Deck4 #BpmText,
+  #DeckCompact4 #BpmText,
+  #DeckMini4 #BpmTextSmall,
+  #Deck4 #KeyText,
+  #DeckCompact4 #KeyText,
+  #DeckMini4 #KeyTextSmall {
   color: #85bdbb;
   }
   #Deck3 WStarRating, #DeckCompact3 WStarRating,
@@ -1457,9 +1480,7 @@ WEffectSelector,
 
   #LibraryContainer QHeaderView {
     border-bottom-right-radius: 1px solid #000;
-    outline: none; /*
-    border-width: 1px 0px 1px 0px;
-    border-image: url(skin:/palemoon/buttons/btn_embedded_library_header.svg) 1 1 1 1;  */
+    outline: none;
   }
   #LibraryContainer QHeaderView::section {
     outline: none;
@@ -1768,8 +1789,8 @@ WPushButton#FxSuperLinkInvertButton[displayValue="0"] {
   }
 
 /* Yellow */
-#RecFeedback[displayValue="1"],   /* initialize recording */
-#BroadcastButton[displayValue="1"]   /* connecting */ {
+#RecFeedback[displayValue="1"],     /* initialize recording */
+#BroadcastButton[displayValue="1"]  /* connecting */ {
   background-color: #d09300;
 }
 
@@ -1778,15 +1799,14 @@ WPushButton#FxSuperLinkInvertButton[displayValue="0"] {
 }
 
 /* pink */
-#BroadcastButton[displayValue="3"],
-#RecFeedback[displayValue="3"] { /* failure */
+#BroadcastButton[displayValue="3"], /* failure */
+#RecFeedback[displayValue="3"] {
   background-color: #f856e7;
 }
 
 /* Grey for GUI toggles */
 #GuiToggleButton[displayValue="1"],
-#SkinSettingsToggle[displayValue="1"] { /*
-  background-color: #216e75; Pale blue */
+#SkinSettingsToggle[displayValue="1"] {
   background-color: #555;
 }
 
diff --git a/src/library/basesqltablemodel.cpp b/src/library/basesqltablemodel.cpp
index 2737ff9dd66..b1314b323d5 100644
--- a/src/library/basesqltablemodel.cpp
+++ b/src/library/basesqltablemodel.cpp
@@ -373,7 +373,7 @@ void BaseSqlTableModel::setTable(const QString& tableName,
     m_bInitialized = true;
 }
 
-int BaseSqlTableModel::columnIndexFromSortColumnId(TrackModel::SortColumnId column) {
+int BaseSqlTableModel::columnIndexFromSortColumnId(TrackModel::SortColumnId column) const {
     if (column == TrackModel::SortColumnId::Invalid) {
         return -1;
     }
@@ -381,7 +381,7 @@ int BaseSqlTableModel::columnIndexFromSortColumnId(TrackModel::SortColumnId colu
     return m_columnIndexBySortColumnId[static_cast<int>(column)];
 }
 
-TrackModel::SortColumnId BaseSqlTableModel::sortColumnIdFromColumnIndex(int index) {
+TrackModel::SortColumnId BaseSqlTableModel::sortColumnIdFromColumnIndex(int index) const {
     return m_sortColumnIdByColumnIndex.value(index, TrackModel::SortColumnId::Invalid);
 }
 
diff --git a/src/library/basesqltablemodel.h b/src/library/basesqltablemodel.h
index 82081abbfa1..a7c46f60897 100644
--- a/src/library/basesqltablemodel.h
+++ b/src/library/basesqltablemodel.h
@@ -58,8 +58,8 @@ class BaseSqlTableModel : public BaseTrackTableModel {
     void search(const QString& searchText, const QString& extraFilter = QString()) override;
     const QString currentSearch() const override;
 
-    TrackModel::SortColumnId sortColumnIdFromColumnIndex(int column) override;
-    int columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) override;
+    TrackModel::SortColumnId sortColumnIdFromColumnIndex(int column) const override;
+    int columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) const override;
 
     void hideTracks(const QModelIndexList& indices) override;
 
diff --git a/src/library/browse/browsetablemodel.cpp b/src/library/browse/browsetablemodel.cpp
index 32ef3cb01a9..a61914b4f49 100644
--- a/src/library/browse/browsetablemodel.cpp
+++ b/src/library/browse/browsetablemodel.cpp
@@ -164,7 +164,7 @@ BrowseTableModel::BrowseTableModel(QObject* parent,
 BrowseTableModel::~BrowseTableModel() {
 }
 
-int BrowseTableModel::columnIndexFromSortColumnId(TrackModel::SortColumnId column) {
+int BrowseTableModel::columnIndexFromSortColumnId(TrackModel::SortColumnId column) const {
     if (column < TrackModel::SortColumnId::IdMin ||
             column >= TrackModel::SortColumnId::IdMax) {
         return -1;
@@ -173,7 +173,7 @@ int BrowseTableModel::columnIndexFromSortColumnId(TrackModel::SortColumnId colum
     return m_columnIndexBySortColumnId[static_cast<int>(column)];
 }
 
-TrackModel::SortColumnId BrowseTableModel::sortColumnIdFromColumnIndex(int index) {
+TrackModel::SortColumnId BrowseTableModel::sortColumnIdFromColumnIndex(int index) const {
     return m_sortColumnIdByColumnIndex.value(index, TrackModel::SortColumnId::Invalid);
 }
 
@@ -460,7 +460,7 @@ void BrowseTableModel::trackLoaded(const QString& group, TrackPointer pTrack) {
     }
 }
 
-bool BrowseTableModel::isColumnSortable(int column) {
+bool BrowseTableModel::isColumnSortable(int column) const {
     return COLUMN_PREVIEW != column;
 }
 
diff --git a/src/library/browse/browsetablemodel.h b/src/library/browse/browsetablemodel.h
index eb95e63c4dd..4df99591e1d 100644
--- a/src/library/browse/browsetablemodel.h
+++ b/src/library/browse/browsetablemodel.h
@@ -69,9 +69,9 @@ class BrowseTableModel final : public QStandardItemModel, public virtual TrackMo
     Qt::ItemFlags flags(const QModelIndex &index) const override;
     bool setData(const QModelIndex& index, const QVariant& value, int role=Qt::EditRole) override;
     QAbstractItemDelegate* delegateForColumn(const int i, QObject* pParent) override;
-    bool isColumnSortable(int column) override;
-    TrackModel::SortColumnId sortColumnIdFromColumnIndex(int index) override;
-    int columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) override;
+    bool isColumnSortable(int column) const override;
+    TrackModel::SortColumnId sortColumnIdFromColumnIndex(int index) const override;
+    int columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) const override;
 
   public slots:
     void slotClear(BrowseTableModel*);
diff --git a/src/library/proxytrackmodel.cpp b/src/library/proxytrackmodel.cpp
index 222b638cd73..fba8a6d6037 100644
--- a/src/library/proxytrackmodel.cpp
+++ b/src/library/proxytrackmodel.cpp
@@ -21,14 +21,14 @@ ProxyTrackModel::ProxyTrackModel(QAbstractItemModel* pTrackModel,
 ProxyTrackModel::~ProxyTrackModel() {
 }
 
-TrackModel::SortColumnId ProxyTrackModel::sortColumnIdFromColumnIndex(int index) {
-    return (m_pTrackModel ? m_pTrackModel->sortColumnIdFromColumnIndex(index)
-                          : TrackModel::sortColumnIdFromColumnIndex(index));
+TrackModel::SortColumnId ProxyTrackModel::sortColumnIdFromColumnIndex(int index) const {
+    return m_pTrackModel ? m_pTrackModel->sortColumnIdFromColumnIndex(index)
+                         : TrackModel::SortColumnId::Invalid;
 }
 
-int ProxyTrackModel::columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) {
-    return (m_pTrackModel ? m_pTrackModel->columnIndexFromSortColumnId(sortColumn)
-                          : TrackModel::columnIndexFromSortColumnId(sortColumn));
+int ProxyTrackModel::columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) const {
+    return m_pTrackModel ? m_pTrackModel->columnIndexFromSortColumnId(sortColumn)
+                         : -1;
 }
 
 TrackId ProxyTrackModel::getTrackId(const QModelIndex& index) const {
diff --git a/src/library/proxytrackmodel.h b/src/library/proxytrackmodel.h
index d0064476d99..542bf93ec05 100644
--- a/src/library/proxytrackmodel.h
+++ b/src/library/proxytrackmodel.h
@@ -38,8 +38,8 @@ class ProxyTrackModel : public QSortFilterProxyModel, public TrackModel {
     QAbstractItemDelegate* delegateForColumn(const int i, QObject* pParent) final;
     QString getModelSetting(const QString& name) final;
     bool setModelSetting(const QString& name, const QVariant& value) final;
-    TrackModel::SortColumnId sortColumnIdFromColumnIndex(int index) override;
-    int columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) override;
+    TrackModel::SortColumnId sortColumnIdFromColumnIndex(int index) const override;
+    int columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) const override;
 
     // Inherited from QSortFilterProxyModel
     bool filterAcceptsRow(int sourceRow, const QModelIndex& sourceParent) const final;
diff --git a/src/library/trackmodel.h b/src/library/trackmodel.h
index ed776b1a740..9b98e51b2db 100644
--- a/src/library/trackmodel.h
+++ b/src/library/trackmodel.h
@@ -184,20 +184,14 @@ class TrackModel {
         m_eDefaultSortOrder = sortOrder;
     }
 
-    virtual bool isColumnSortable(int column) {
+    virtual bool isColumnSortable(int column) const {
         Q_UNUSED(column);
         return true;
     }
 
-    virtual SortColumnId sortColumnIdFromColumnIndex(int index) {
-        Q_UNUSED(index);
-        return TrackModel::SortColumnId::Invalid;
-    }
+    virtual SortColumnId sortColumnIdFromColumnIndex(int index) const = 0;
 
-    virtual int columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) {
-        Q_UNUSED(sortColumn);
-        return -1;
-    }
+    virtual int columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) const = 0;
 
     virtual int fieldIndex(const QString& fieldName) const {
         Q_UNUSED(fieldName);
diff --git a/src/preferences/dialog/dlgprefrecord.cpp b/src/preferences/dialog/dlgprefrecord.cpp
index 1df36538edc..533520f293c 100644
--- a/src/preferences/dialog/dlgprefrecord.cpp
+++ b/src/preferences/dialog/dlgprefrecord.cpp
@@ -24,12 +24,13 @@ DlgPrefRecord::DlgPrefRecord(QWidget* parent, UserSettingsPointer pConfig)
 
     // Setting recordings path.
     QString recordingsPath = m_pConfig->getValueString(ConfigKey(RECORDING_PREF_KEY, "Directory"));
-    if (recordingsPath == "") {
+    if (recordingsPath.isEmpty()) {
         // Initialize recordings path in config to old default path.
         // Do it here so we show current value in UI correctly.
         QString musicDir = QStandardPaths::writableLocation(QStandardPaths::MusicLocation);
         QDir recordDir(musicDir + "/Mixxx/Recordings");
         recordingsPath = recordDir.absolutePath();
+        m_pConfig->setValue(ConfigKey(RECORDING_PREF_KEY, "Directory"), recordingsPath);
     }
     LineEditRecordings->setText(recordingsPath);
     connect(PushButtonBrowseRecordings,
@@ -383,13 +384,32 @@ void DlgPrefRecord::loadMetaData() {
 
 void DlgPrefRecord::saveRecordingFolder()
 {
-    if (LineEditRecordings->text() == "") {
-        qDebug() << "Recordings path was empty in dialog";
-        return;
-    }
-    if (LineEditRecordings->text() != m_pConfig->getValueString(ConfigKey(RECORDING_PREF_KEY, "Directory"))) {
-        qDebug() << "Saved recordings path" << LineEditRecordings->text();
-        m_pConfig->set(ConfigKey(RECORDING_PREF_KEY, "Directory"), LineEditRecordings->text());
+    QString newPath = LineEditRecordings->text();
+    if (newPath != m_pConfig->getValueString(ConfigKey(RECORDING_PREF_KEY, "Directory"))) {
+        QFileInfo fileInfo(newPath);
+        if (!fileInfo.exists()) {
+            QMessageBox::warning(
+                    this,
+                    tr("Recordings directory invalid"),
+                    tr("Recordings directory must be set to an existing directory."));
+            return;
+        }
+        if (!fileInfo.isDir()) {
+            QMessageBox::warning(
+                    this,
+                    tr("Recordings directory invalid"),
+                    tr("Recordings directory must be set to a directory."));
+            return;
+        }
+        if (!fileInfo.isWritable()) {
+            QMessageBox::warning(this,
+                    tr("Recordings directory not writable"),
+                    tr("You do not have write access to %1. Choose a "
+                       "recordings directory you have write access to.")
+                            .arg(newPath));
+            return;
+        }
+        m_pConfig->set(ConfigKey(RECORDING_PREF_KEY, "Directory"), newPath);
     }
 }
 void DlgPrefRecord::saveMetaData()
diff --git a/src/track/cue.cpp b/src/track/cue.cpp
index ecb23f3425d..d844e55606c 100644
--- a/src/track/cue.cpp
+++ b/src/track/cue.cpp
@@ -15,7 +15,7 @@ inline std::optional<double> positionSamplesToMillis(
         double positionSamples,
         mixxx::audio::SampleRate sampleRate) {
     VERIFY_OR_DEBUG_ASSERT(sampleRate.isValid()) {
-        return Cue::kNoPosition;
+        return std::nullopt;
     }
     if (positionSamples == Cue::kNoPosition) {
         return std::nullopt;
diff --git a/src/util/qt.h b/src/util/qt.h
index b9817e957ef..f674d6d7ddb 100644
--- a/src/util/qt.h
+++ b/src/util/qt.h
@@ -51,7 +51,7 @@ class SafeQPointer final {
             : m_ptr(ptr) {
     }
 
-    void clear() const {
+    void clear() {
         m_ptr.clear();
     }