diff --git a/toonz/sources/toonz/matchlinecommand.cpp b/toonz/sources/toonz/matchlinecommand.cpp
index f77ded0..d1156b3 100644
--- a/toonz/sources/toonz/matchlinecommand.cpp
+++ b/toonz/sources/toonz/matchlinecommand.cpp
@@ -106,24 +106,11 @@ bool isVectorColumn(const std::set<int> &columns) {
   std::set<int>::const_iterator column = columns.begin();
   int start, end;
   xsh->getCellRange(*column, start, end);
-  
-  if (start > end) return false;
-  
-  std::vector<TXshCell> cell(end - start + 1);
-  xsh->getCells(start, *column, cell.size(), &(cell[0]));
-  
-  TXshSimpleLevel *level = 0;
-  for (int i = 0; i < (int)cell.size(); i++) {
-    if (cell[i].isEmpty()) continue;
-
-    level = cell[i].getSimpleLevel();
-    if (level->getType() == PLI_XSHLEVEL) {
-      return true;
-    } else {
-      return false;
-    }
-  }
 
+  if (start > end) return false;
+  // a cell at "start" must be occupied
+  TXshCell cell = xsh->getCell(start, *column);
+  return cell.m_level->getType() == PLI_XSHLEVEL;
 }
 
 class MergeColumnsCommand final : public MenuItemHandler {
@@ -150,16 +137,19 @@ public:
           "only one columns is selected."));
       return;
     }
-    
+
     bool groupLevels = true;
     if (isVectorColumn(indices)) {
-      int opt = DVGui::MsgBox("Group strokes by vector levels?", QObject::tr("Yes"), QObject::tr("No"), QObject::tr("Cancel"));
-      if (opt == 3) return;
+      int opt = DVGui::MsgBox(QObject::tr("Group strokes by vector levels?"),
+                              QObject::tr("Yes"), QObject::tr("No"),
+                              QObject::tr("Cancel"));
+      if (opt == 0 || opt == 3)
+        return;
       else {
         groupLevels = (opt == 1);
       };
     }
-    
+
     mergeColumns(indices, groupLevels);
     TApp::instance()->getCurrentXsheet()->notifyXsheetChanged();
   }
@@ -345,10 +335,10 @@ void doCloneLevelNoSave(const TCellSelection::Range &range,
       fid = cell.getFrameId();
 
       if (cell.getSimpleLevel() == 0 ||
-          cell.getSimpleLevel()->getPath().getType() == "psd" || 
-		  cell.getSimpleLevel()->getPath().getType() == "gif" || 
-		  cell.getSimpleLevel()->getPath().getType() == "mp4" || 
-		  cell.getSimpleLevel()->getPath().getType() == "webm")
+          cell.getSimpleLevel()->getPath().getType() == "psd" ||
+          cell.getSimpleLevel()->getPath().getType() == "gif" ||
+          cell.getSimpleLevel()->getPath().getType() == "mp4" ||
+          cell.getSimpleLevel()->getPath().getType() == "webm")
         continue;
 
       std::map<TXshSimpleLevel *, TXshLevelP>::iterator it =
diff --git a/toonz/sources/toonz/mergecolumns.cpp b/toonz/sources/toonz/mergecolumns.cpp
index e280ce6..47399eb 100644
--- a/toonz/sources/toonz/mergecolumns.cpp
+++ b/toonz/sources/toonz/mergecolumns.cpp
@@ -144,7 +144,8 @@ bool needTobeGrouped(const TVectorImageP &vimg) {
 
 //---------------------------------------------------------------------------------------
 
-void mergeVectorColumns(const std::vector<MatchlinePair> &matchingLevels, bool groupLevels) {
+void mergeVectorColumns(const std::vector<MatchlinePair> &matchingLevels,
+                        bool groupLevels) {
   if (matchingLevels.empty()) return;
 
   int i = 0;
@@ -157,7 +158,8 @@ void mergeVectorColumns(const std::vector<MatchlinePair> &matchingLevels, bool g
       throw TRopException("Cannot merge columns of different image types!");
     // img->lock();
 
-    if (needTobeGrouped(vimg) && groupLevels) vimg->group(0, vimg->getStrokeCount());
+    if (needTobeGrouped(vimg) && groupLevels)
+      vimg->group(0, vimg->getStrokeCount());
     bool ungroup = false;
     if (needTobeGrouped(vmatch) && groupLevels) {
       ungroup = true;
@@ -199,7 +201,7 @@ public:
       , m_mColumn(mColumn)
       , m_images(images)
       , m_palette(palette->clone())
-	  , m_groupLevels(groupLevels) {}
+      , m_groupLevels(groupLevels) {}
 
   void undo() const override {
     QApplication::setOverrideCursor(Qt::WaitCursor);
@@ -245,7 +247,10 @@ public:
   }
 
   QString getHistoryString() override {
-    return QObject::tr("Merge Raster Levels");
+    if (m_level->getType() == PLI_XSHLEVEL)
+      return QObject::tr("Merge Vector Levels");
+    else
+      return QObject::tr("Merge Raster Levels");
   }
   int getHistoryType() override { return HistoryType::FilmStrip; }
 };
@@ -262,7 +267,8 @@ void mergeColumns(const std::set<int> &columns, bool groupLevels) {
 
   TUndoManager::manager()->beginBlock();
 
-  for (; it != columns.end(); ++it) mergeColumns(dstColumn, *it, false, groupLevels);
+  for (; it != columns.end(); ++it)
+    mergeColumns(dstColumn, *it, false, groupLevels);
 
   TUndoManager::manager()->endBlock();
 
@@ -381,10 +387,6 @@ void mergeColumns(int column, int mColumn, bool isRedo, bool groupLevels) {
     return;
   }
 
-  ToonzScene *sc = TApp::instance()->getCurrentScene()->getScene();
-  TXshSimpleLevel *simpleLevel =
-      sc->getLevelSet()->getLevel(column)->getSimpleLevel();
-
   if (!isRedo)
     TUndoManager::manager()->add(
         new MergeColumnsUndo(xl, MergeColumnsSessionId, column, level, images,
@@ -403,13 +405,8 @@ void mergeColumns(int column, int mColumn, bool isRedo, bool groupLevels) {
   } else
     mergeVectorColumns(matchingLevels, groupLevels);
 
-  TXshLevel *sl =
-      TApp::instance()->getCurrentScene()->getScene()->getLevelSet()->getLevel(
-          column);
-  std::vector<TFrameId> fidsss;
-  sl->getFids(fidsss);
-  invalidateIcons(sl, fidsss);
-  sl->setDirtyFlag(true);
+  std::vector<TFrameId> fids(alreadyDoneSet.begin(), alreadyDoneSet.end());
+  invalidateIcons(level, fids);
   level->setDirtyFlag(true);
   TApp::instance()->getCurrentXsheet()->notifyXsheetChanged();
 }