diff --git a/src/Gui/Application.cpp b/src/Gui/Application.cpp
index bf26e49e1b..e8fbd99d3b 100644
--- a/src/Gui/Application.cpp
+++ b/src/Gui/Application.cpp
@@ -2602,7 +2602,7 @@ App::Document* Application::reopen(App::Document* doc)
         if (name == v.first->FileName.getValue()) {
             doc = const_cast<App::Document*>(v.first);
         }
-        if (untouchedDocs.count(v.second)) {
+        if (untouchedDocs.contains(v.second)) {
             if (!v.second->isModified()) {
                 continue;
             }
diff --git a/src/Gui/Command.cpp b/src/Gui/Command.cpp
index c434a9cfe6..301386060a 100644
--- a/src/Gui/Command.cpp
+++ b/src/Gui/Command.cpp
@@ -1977,7 +1977,7 @@ const Command* Gui::CommandManager::checkAcceleratorForConflicts(const char* acc
     if (newCombo.isEmpty())
         return nullptr;
     auto newSequence = QKeySequence::fromString(newCombo);
-    if (newSequence.count() == 0)
+    if (newSequence.isEmpty())
         return nullptr;
 
     // Does this command shortcut conflict with other commands already defined?
@@ -1998,7 +1998,7 @@ const Command* Gui::CommandManager::checkAcceleratorForConflicts(const char* acc
         if (existingCombo.isEmpty())
             continue;
         auto existingSequence = QKeySequence::fromString(existingCombo);
-        if (existingSequence.count() == 0)
+        if (existingSequence.isEmpty())
             continue;
 
         // Exact match
diff --git a/src/Gui/CommandLink.cpp b/src/Gui/CommandLink.cpp
index d0c1baea59..42f9252887 100644
--- a/src/Gui/CommandLink.cpp
+++ b/src/Gui/CommandLink.cpp
@@ -403,7 +403,7 @@ static void linkConvert(bool unlink) {
             auto obj = info.obj.getObject();
             if(!parent || !obj || !parentVp)
                 continue;
-            if(!recomputeSet.count(parent))
+            if(!recomputeSet.contains(parent))
                 recomputeSet.emplace(parent,parent);
             auto doc = parent->getDocument();
             App::DocumentObject *replaceObj;
diff --git a/src/Gui/DAGView/DAGModel.cpp b/src/Gui/DAGView/DAGModel.cpp
index 887ba29922..d608194d58 100644
--- a/src/Gui/DAGView/DAGModel.cpp
+++ b/src/Gui/DAGView/DAGModel.cpp
@@ -1096,7 +1096,7 @@ void Model::contextMenuEvent(QGraphicsSceneContextMenuEvent* event)
         contextMenu.addAction(editingFinishedAction);
     }
 
-    if (contextMenu.actions().count() > 0)
+    if (!contextMenu.actions().isEmpty())
         contextMenu.exec(event->screenPos());
   }
 
diff --git a/src/Gui/Dialogs/DlgObjectSelection.cpp b/src/Gui/Dialogs/DlgObjectSelection.cpp
index a7cc6f5332..158a69bb15 100644
--- a/src/Gui/Dialogs/DlgObjectSelection.cpp
+++ b/src/Gui/Dialogs/DlgObjectSelection.cpp
@@ -280,7 +280,7 @@ void DlgObjectSelection::setItemState(App::DocumentObject *obj,
     if (ui->checkBoxAutoDeps->isChecked() && state == Qt::Checked) {
         // If an object is newly checked, check all its dependencies
         for (auto o : obj->getOutListRecursive()) {
-            if (!depSet.count(o) || itemChanged.count(o))
+            if (!depSet.contains(o) || itemChanged.contains(o))
                 continue;
             auto itItem = itemMap.find(o);
             if (itItem == itemMap.end() || itItem->second[0]->checkState(0) == state)
@@ -304,7 +304,7 @@ void DlgObjectSelection::setItemState(App::DocumentObject *obj,
         // If an object toggles state, we need to revisit all its in-list
         // object to update the partial/full checked state.
         for (auto o : obj->getInList()) {
-            if (!depSet.count(o) ||itemChanged.count(o))
+            if (!depSet.contains(o) || itemChanged.contains(o))
                 continue;
             auto it = itemMap.find(o);
             if (it == itemMap.end() || it->second[0]->checkState(0) == state)
@@ -312,7 +312,7 @@ void DlgObjectSelection::setItemState(App::DocumentObject *obj,
             int count = 0;
             int selcount = 0;
             for (auto sibling : o->getOutList()) {
-                if (!depSet.count(sibling))
+                if (!depSet.contains(sibling))
                     continue;
                 ++count;
                 auto it = itemMap.find(sibling);
@@ -511,7 +511,7 @@ void DlgObjectSelection::checkItemChanged() {
         std::sort(outlist.begin(), outlist.end());
 
         for (const auto &v : itemMap) {
-            if (itemChanged.count(v.first) == 0 && v.second[0]->checkState(0) == Qt::Unchecked)
+            if (!itemChanged.contains(v.first) && v.second[0]->checkState(0) == Qt::Unchecked)
                 continue;
             if (auto obj = v.first.getObject()) {
                 if (!std::binary_search(outlist.begin(), outlist.end(), obj))
@@ -598,7 +598,7 @@ void DlgObjectSelection::onItemSelectionChanged() {
     for (auto obj : sels)
         obj->getInListEx(inlist, true);
     for (auto it = inlist.begin(); it != inlist.end();) {
-        if (!depSet.count(*it) || std::binary_search(sels.begin(), sels.end(), *it))
+        if (!depSet.contains(*it) || std::binary_search(sels.begin(), sels.end(), *it))
             it = inlist.erase(it);
         else
             ++it;
diff --git a/src/Gui/Dialogs/DlgOnlineHelpImp.cpp b/src/Gui/Dialogs/DlgOnlineHelpImp.cpp
index 94f0808b98..c76cd2abf5 100644
--- a/src/Gui/Dialogs/DlgOnlineHelpImp.cpp
+++ b/src/Gui/Dialogs/DlgOnlineHelpImp.cpp
@@ -98,7 +98,7 @@ void DlgOnlineHelpImp::changeEvent(QEvent *e)
 void DlgOnlineHelpImp::onLineEditDownloadFileNameSelected( const QString& url )
 {
     QDir dir(url);
-    if (dir.exists() && dir.count() == 0) {
+    if (dir.exists() && dir.isEmpty()) {
         QMessageBox::critical(this, tr("Access denied"), tr("Access denied to '%1'\n\n"
             "Specify another directory, please.").arg(url));
     }
diff --git a/src/Gui/Document.cpp b/src/Gui/Document.cpp
index bbfcb7f0fb..546093c4e8 100644
--- a/src/Gui/Document.cpp
+++ b/src/Gui/Document.cpp
@@ -1047,7 +1047,7 @@ void Document::slotChangedObject(const App::DocumentObject& Obj, const App::Prop
                     && (Prop.isDerivedFrom<App::PropertyPlacement>()
                         // Issue ID 0004230 : getName() can return null in which case strstr() crashes
                         || (Prop.getName() && strstr(Prop.getName(),"Scale")))
-                    && d->_editObjs.count(&Obj))
+                    && d->_editObjs.contains(&Obj))
             {
                 Base::Matrix4D mat;
                 auto sobj = d->_editViewProviderParent->getObject()->getSubObject(
@@ -1294,7 +1294,7 @@ static bool checkCanonicalPath(const std::map<App::Document*, bool> &docs)
         auto &d = paths[info.canonicalFilePath()];
         d.push_back(doc);
         if (!warn && d.size() > 1) {
-            if (docs.count(d.front()) || docs.count(d.back()))
+            if (docs.contains(d.front()) || docs.contains(d.back()))
                 warn = true;
         }
     }
@@ -1315,7 +1315,7 @@ static bool checkCanonicalPath(const std::map<App::Document*, bool> &docs)
     for (auto &v : paths) {
         if (v.second.size() <= 1) continue;
         for (auto doc : v.second) {
-            if (docs.count(doc)) {
+            if (docs.contains(doc)) {
                 FC_WARN("Physical path: " << v.first.toUtf8().constData());
                 for (auto d : v.second)
                     FC_WARN("  Document: " << docName(d).toUtf8().constData()
diff --git a/src/Gui/ExpressionCompleter.cpp b/src/Gui/ExpressionCompleter.cpp
index 44c0e65983..cb3e409545 100644
--- a/src/Gui/ExpressionCompleter.cpp
+++ b/src/Gui/ExpressionCompleter.cpp
@@ -341,7 +341,7 @@ public:
             if (idx >= 0 && idx < objSize) {
                 obj = objs[idx / 2];
                 // if they are in the ignore list skip
-                if (inList.count(obj)) {
+                if (inList.contains(obj)) {
                     return;
                 }
             }
@@ -430,7 +430,7 @@ public:
             const auto& objs = doc->getObjects();
             objSize = (int)objs.size() * 2;
             // if invalid index, or in the ignore list bail out
-            if (idx < 0 || idx >= objSize || inList.count(obj)) {
+            if (idx < 0 || idx >= objSize || inList.contains(obj)) {
                 return;
             }
             obj = objs[idx / 2];
diff --git a/src/Gui/MDIViewPyWrap.cpp b/src/Gui/MDIViewPyWrap.cpp
index 0be622db10..77376f9f83 100644
--- a/src/Gui/MDIViewPyWrap.cpp
+++ b/src/Gui/MDIViewPyWrap.cpp
@@ -66,7 +66,7 @@ public:
         Base::PyGILStateLocker lock;
         PythonWrapper wrap;
         wrap.loadWidgetsModule();
-        if (func.count("widget") == 0) {
+        if (!func.contains("widget")) {
             throw Py::AttributeError("Object has no attribute 'widget'");
         }
         Py::Callable target(func.at("widget"));
diff --git a/src/Gui/MenuManager.cpp b/src/Gui/MenuManager.cpp
index db6ae93325..e0520d0e57 100644
--- a/src/Gui/MenuManager.cpp
+++ b/src/Gui/MenuManager.cpp
@@ -62,7 +62,7 @@ std::string MenuItem::command() const
 
 bool MenuItem::hasItems() const
 {
-    return _items.count() > 0;
+    return !_items.isEmpty();
 }
 
 MenuItem* MenuItem::findItem(const std::string& name)
diff --git a/src/Gui/OverlayManager.cpp b/src/Gui/OverlayManager.cpp
index 2f12fea611..8c1cb144e7 100644
--- a/src/Gui/OverlayManager.cpp
+++ b/src/Gui/OverlayManager.cpp
@@ -1179,7 +1179,7 @@ public:
                 if (dockWidget == dock
                         || !dockWidget->isVisible()
                         || dockWidget->isFloating()
-                        || _overlayMap.count(dockWidget))
+                        || _overlayMap.contains(dockWidget))
                     continue;
                 if (dockWidget->rect().contains(dockWidget->mapFromGlobal(pos))) {
                     dstDock = dockWidget;
diff --git a/src/Gui/PropertyView.cpp b/src/Gui/PropertyView.cpp
index 9f1094243e..315d339c3d 100644
--- a/src/Gui/PropertyView.cpp
+++ b/src/Gui/PropertyView.cpp
@@ -214,7 +214,7 @@ void PropertyView::slotRollback() {
 
 void PropertyView::slotChangePropertyData(const App::Property& prop)
 {
-    if (propertyEditorData->propOwners.count(prop.getContainer())) {
+    if (propertyEditorData->propOwners.contains(prop.getContainer())) {
         propertyEditorData->updateProperty(prop);
         timer->start(ViewParams::instance()->getPropertyViewTimer());
     }
@@ -222,7 +222,7 @@ void PropertyView::slotChangePropertyData(const App::Property& prop)
 
 void PropertyView::slotChangePropertyView(const Gui::ViewProvider&, const App::Property& prop)
 {
-    if (propertyEditorView->propOwners.count(prop.getContainer())) {
+    if (propertyEditorView->propOwners.contains(prop.getContainer())) {
         propertyEditorView->updateProperty(prop);
         timer->start(ViewParams::instance()->getPropertyViewTimer());
     }
@@ -239,8 +239,8 @@ void PropertyView::slotAppendDynamicProperty(const App::Property& prop)
         return;
 
     App::PropertyContainer* parent = prop.getContainer();
-    if (propertyEditorData->propOwners.count(parent)
-            || propertyEditorView->propOwners.count(parent))
+    if (propertyEditorData->propOwners.contains(parent)
+            || propertyEditorView->propOwners.contains(parent))
     {
         timer->start(ViewParams::instance()->getPropertyViewTimer());
     }
@@ -249,9 +249,9 @@ void PropertyView::slotAppendDynamicProperty(const App::Property& prop)
 void PropertyView::slotRemoveDynamicProperty(const App::Property& prop)
 {
     App::PropertyContainer* parent = prop.getContainer();
-    if(propertyEditorData->propOwners.count(parent))
+    if(propertyEditorData->propOwners.contains(parent))
         propertyEditorData->removeProperty(prop);
-    else if(propertyEditorView->propOwners.count(parent))
+    else if(propertyEditorView->propOwners.contains(parent))
         propertyEditorView->removeProperty(prop);
     else
         return;
@@ -261,13 +261,13 @@ void PropertyView::slotRemoveDynamicProperty(const App::Property& prop)
 void PropertyView::slotChangePropertyEditor(const App::Document &, const App::Property& prop)
 {
     App::PropertyContainer* parent = prop.getContainer();
-    if (propertyEditorData->propOwners.count(parent)
-            || propertyEditorView->propOwners.count(parent))
+    if (propertyEditorData->propOwners.contains(parent)
+            || propertyEditorView->propOwners.contains(parent))
         timer->start(ViewParams::instance()->getPropertyViewTimer());
 }
 
 void PropertyView::slotDeleteDocument(const Gui::Document &doc) {
-    if(propertyEditorData->propOwners.count(doc.getDocument())) {
+    if(propertyEditorData->propOwners.contains(doc.getDocument())) {
         propertyEditorView->buildUp();
         propertyEditorData->buildUp();
         clearPropertyItemSelection();
@@ -276,7 +276,7 @@ void PropertyView::slotDeleteDocument(const Gui::Document &doc) {
 }
 
 void PropertyView::slotDeletedViewObject(const Gui::ViewProvider &vp) {
-    if(propertyEditorView->propOwners.count(&vp)) {
+    if(propertyEditorView->propOwners.contains(&vp)) {
         propertyEditorView->buildUp();
         propertyEditorData->buildUp();
         clearPropertyItemSelection();
@@ -285,7 +285,7 @@ void PropertyView::slotDeletedViewObject(const Gui::ViewProvider &vp) {
 }
 
 void PropertyView::slotDeletedObject(const App::DocumentObject &obj) {
-    if(propertyEditorData->propOwners.count(&obj)) {
+    if(propertyEditorData->propOwners.contains(&obj)) {
         propertyEditorView->buildUp();
         propertyEditorData->buildUp();
         clearPropertyItemSelection();
diff --git a/src/Gui/Selection/SoFCSelectionContext.cpp b/src/Gui/Selection/SoFCSelectionContext.cpp
index 8ab9a3886f..241d2d488f 100644
--- a/src/Gui/Selection/SoFCSelectionContext.cpp
+++ b/src/Gui/Selection/SoFCSelectionContext.cpp
@@ -104,7 +104,7 @@ int SoFCSelectionContext::merge(int status, SoFCSelectionContextBasePtr &output,
 
     std::vector<int> remove;
     for(auto idx : ret->selectionIndex) {
-        if(!ctx->selectionIndex.count(idx))
+        if(!ctx->selectionIndex.contains(idx))
             remove.push_back(idx);
     }
 
@@ -216,7 +216,7 @@ int SoFCSelectionContextEx::merge(int status, SoFCSelectionContextBasePtr &outpu
     auto ret = std::dynamic_pointer_cast<SoFCSelectionContextEx>(output);
     assert(ret);
     for(auto &v : ctx->colors) {
-        if(ret->colors.count(v.first))
+        if(ret->colors.contains(v.first))
             continue;
         if(!status) {
             status = 1;
diff --git a/src/Gui/ToolBarManager.cpp b/src/Gui/ToolBarManager.cpp
index ee01114b36..0b2ade5b05 100644
--- a/src/Gui/ToolBarManager.cpp
+++ b/src/Gui/ToolBarManager.cpp
@@ -78,7 +78,7 @@ const std::string & ToolBarItem::command() const
 
 bool ToolBarItem::hasItems() const
 {
-    return _items.count() > 0;
+    return !_items.isEmpty();
 }
 
 ToolBarItem* ToolBarItem::findItem(const std::string& name)
diff --git a/src/Gui/Tree.cpp b/src/Gui/Tree.cpp
index 5e7ee7bf83..88b82d6345 100644
--- a/src/Gui/Tree.cpp
+++ b/src/Gui/Tree.cpp
@@ -1177,7 +1177,7 @@ void TreeWidget::contextMenuEvent(QContextMenuEvent* e)
         header()->setVisible(action->isChecked()||internalNameAction->isChecked());
     });
 
-    if (contextMenu.actions().count() > 0) {
+    if (!contextMenu.actions().isEmpty()) {
         try {
             contextMenu.exec(QCursor::pos());
         }
@@ -2573,7 +2573,7 @@ bool TreeWidget::dropInObject(QDropEvent* event, TargetItemInfo& targetInfo,
                 }
             }
 
-            if (inList.count(obj)) {
+            if (inList.contains(obj)) {
                 FC_THROWM(Base::RuntimeError, "Dependency loop detected for " << obj->getFullName());
             }
 
@@ -3059,7 +3059,7 @@ void TreeWidget::onUpdateStatus()
                 continue;
             if (obj->isError())
                 errors.push_back(obj);
-            if (docItem->ObjectMap.count(obj))
+            if (docItem->ObjectMap.contains(obj))
                 continue;
             auto vpd = freecad_cast<ViewProviderDocumentObject*>(gdoc->getViewProvider(obj));
             if (vpd)
@@ -4447,7 +4447,7 @@ void TreeWidget::updateChildren(App::DocumentObject* obj,
         // and thus, its property change will not be propagated through
         // recomputation. So we have to manually check for each links here.
         for (auto link : App::GetApplication().getLinksTo(obj, App::GetLinkRecursive)) {
-            if (ChangedObjects.count(link))
+            if (ChangedObjects.contains(link))
                 continue;
             std::vector<App::DocumentObject*> linkedChildren;
             DocumentObjectDataPtr found;
@@ -4475,7 +4475,7 @@ void TreeWidget::updateChildren(App::DocumentObject* obj,
         //if the item is in a GeoFeatureGroup we may need to update that too, as the claim children
         //of the geofeaturegroup depends on what the childs claim
         auto grp = App::GeoFeatureGroupExtension::getGroupOfObject(obj);
-        if (grp && !ChangedObjects.count(grp)) {
+        if (grp && !ChangedObjects.contains(grp)) {
             auto iter = ObjectTable.find(grp);
             if (iter != ObjectTable.end())
                 updateChildren(grp, iter->second, true, false);
diff --git a/src/Gui/ViewProviderGeoFeatureGroupExtension.cpp b/src/Gui/ViewProviderGeoFeatureGroupExtension.cpp
index e441220f4b..608847e413 100644
--- a/src/Gui/ViewProviderGeoFeatureGroupExtension.cpp
+++ b/src/Gui/ViewProviderGeoFeatureGroupExtension.cpp
@@ -104,7 +104,7 @@ std::vector<App::DocumentObject*> ViewProviderGeoFeatureGroupExtension::extensio
     for(auto obj : model) {
         if(!obj || !obj->isAttachedToDocument())
             continue;
-        if(outSet.count(obj))
+        if(outSet.contains(obj))
             obj->setStatus(App::ObjectStatus::GeoExcluded,true);
         else {
             obj->setStatus(App::ObjectStatus::GeoExcluded,false);