3 files changed, 69 insertions, 5 deletions

diff --git a/src/widgets/styles/qfusionstyle.cpp b/src/widgets/styles/qfusionstyle.cpp
index 49b3703189..03d083bbf1 100644
--- a/src/widgets/styles/qfusionstyle.cpp
+++ b/src/widgets/styles/qfusionstyle.cpp
@@ -1590,7 +1590,7 @@ void QFusionStyle::drawControl(ControlElement element, const QStyleOption *optio
                 (option->styleObject && option->styleObject->property("_q_isComboBoxPopupItem").toBool()))
                 ignoreCheckMark = true; //ignore the checkmarks provided by the QComboMenuDelegate
 
-            if (!ignoreCheckMark) {
+            if (!ignoreCheckMark || menuItem->state & (State_On | State_Off)) {
                 // Check, using qreal and QRectF to avoid error accumulation
                 const qreal boxMargin = dpiScaled(3.5, option);
                 const qreal boxWidth = checkcol - 2 * boxMargin;
@@ -1601,7 +1601,7 @@ void QFusionStyle::drawControl(ControlElement element, const QStyleOption *optio
                 if (checkable) {
                     if (menuItem->checkType & QStyleOptionMenuItem::Exclusive) {
                         // Radio button
-                        if (checked || sunken) {
+                        if (menuItem->state & State_On || checked || sunken) {
                             painter->setRenderHint(QPainter::Antialiasing);
                             painter->setPen(Qt::NoPen);
 
@@ -1617,8 +1617,10 @@ void QFusionStyle::drawControl(ControlElement element, const QStyleOption *optio
                             QStyleOptionButton box;
                             box.QStyleOption::operator=(*option);
                             box.rect = checkRect;
-                            if (checked)
+                            if (checked || menuItem->state & State_On)
                                 box.state |= State_On;
+                            else
+                                box.state |= State_Off;
                             proxy()->drawPrimitive(PE_IndicatorCheckBox, &box, painter, widget);
                         }
                     }
diff --git a/src/widgets/widgets/qcombobox.cpp b/src/widgets/widgets/qcombobox.cpp
index 19b442f477..4cfa5554e4 100644
--- a/src/widgets/widgets/qcombobox.cpp
+++ b/src/widgets/widgets/qcombobox.cpp
@@ -129,7 +129,15 @@ QStyleOptionMenuItem QComboMenuDelegate::getStyleOption(const QStyleOptionViewIt
     if (option.state & QStyle::State_Selected)
         menuOption.state |= QStyle::State_Selected;
     menuOption.checkType = QStyleOptionMenuItem::NonExclusive;
-    menuOption.checked = mCombo->currentIndex() == index.row();
+    // a valid checkstate means that the model has checkable items
+    const QVariant checkState = index.data(Qt::CheckStateRole);
+    if (!checkState.isValid()) {
+        menuOption.checked = mCombo->currentIndex() == index.row();
+    } else {
+        menuOption.checked = qvariant_cast<int>(checkState) == Qt::Checked;
+        menuOption.state |= qvariant_cast<int>(checkState) == Qt::Checked
+                          ? QStyle::State_On : QStyle::State_Off;
+    }
     if (QComboBoxDelegate::isSeparator(index))
         menuOption.menuItemType = QStyleOptionMenuItem::Separator;
     else
@@ -179,6 +187,55 @@ QStyleOptionMenuItem QComboMenuDelegate::getStyleOption(const QStyleOptionViewIt
     return menuOption;
 }
 
+bool QComboMenuDelegate::editorEvent(QEvent *event, QAbstractItemModel *model,
+                                     const QStyleOptionViewItem &option, const QModelIndex &index)
+{
+    Q_ASSERT(event);
+    Q_ASSERT(model);
+
+    // make sure that the item is checkable
+    Qt::ItemFlags flags = model->flags(index);
+    if (!(flags & Qt::ItemIsUserCheckable) || !(option.state & QStyle::State_Enabled)
+        || !(flags & Qt::ItemIsEnabled))
+        return false;
+
+    // make sure that we have a check state
+    const QVariant checkState = index.data(Qt::CheckStateRole);
+    if (!checkState.isValid())
+        return false;
+
+    // make sure that we have the right event type
+    if ((event->type() == QEvent::MouseButtonRelease)
+        || (event->type() == QEvent::MouseButtonDblClick)
+        || (event->type() == QEvent::MouseButtonPress)) {
+        QMouseEvent *me = static_cast<QMouseEvent*>(event);
+        if (me->button() != Qt::LeftButton)
+            return false;
+
+        if ((event->type() == QEvent::MouseButtonPress)
+            || (event->type() == QEvent::MouseButtonDblClick)) {
+            pressedIndex = index.row();
+            return false;
+        }
+
+        if (index.row() != pressedIndex)
+            return false;
+        pressedIndex = -1;
+
+    } else if (event->type() == QEvent::KeyPress) {
+        if (static_cast<QKeyEvent*>(event)->key() != Qt::Key_Space
+         && static_cast<QKeyEvent*>(event)->key() != Qt::Key_Select)
+            return false;
+    } else {
+        return false;
+    }
+
+    // we don't support user-tristate items in QComboBox (not implemented in any style)
+    Qt::CheckState newState = (static_cast<Qt::CheckState>(checkState.toInt()) == Qt::Checked)
+                            ? Qt::Unchecked : Qt::Checked;
+    return model->setData(index, newState, Qt::CheckStateRole);
+}
+
 #if QT_CONFIG(completer)
 void QComboBoxPrivate::_q_completerActivated(const QModelIndex &index)
 {
diff --git a/src/widgets/widgets/qcombobox_p.h b/src/widgets/widgets/qcombobox_p.h
index c79406eafd..7a3fcf6e0f 100644
--- a/src/widgets/widgets/qcombobox_p.h
+++ b/src/widgets/widgets/qcombobox_p.h
@@ -266,7 +266,9 @@ class Q_AUTOTEST_EXPORT QComboMenuDelegate : public QAbstractItemDelegate
 {
     Q_OBJECT
 public:
-    QComboMenuDelegate(QObject *parent, QComboBox *cmb) : QAbstractItemDelegate(parent), mCombo(cmb) {}
+    QComboMenuDelegate(QObject *parent, QComboBox *cmb)
+    : QAbstractItemDelegate(parent), mCombo(cmb), pressedIndex(-1)
+    {}
 
 protected:
     void paint(QPainter *painter,
@@ -282,11 +284,14 @@ protected:
         return mCombo->style()->sizeFromContents(
             QStyle::CT_MenuItem, &opt, option.rect.size(), mCombo);
     }
+    bool editorEvent(QEvent *event, QAbstractItemModel *model,
+                     const QStyleOptionViewItem &option, const QModelIndex &index) override;
 
 private:
     QStyleOptionMenuItem getStyleOption(const QStyleOptionViewItem &option,
                                         const QModelIndex &index) const;
     QComboBox *mCombo;
+    int pressedIndex;
 };
 
 // ### Qt6: QStyledItemDelegate ?