Add custom property when pressing Enter with type combo focused

This change also disables Enter for opening the combo box popup, fixing
the rather broken behavior (at least on Linux) that pressing Enter to
select a type will immediately re-open the popup. That only applies to
combo boxes in the Properties view, though.

src/tiled/propertyeditorwidgets.cpp

@@ -288,6 +288,18 @@ bool ComboBox::event(QEvent *event)
     return QComboBox::event(event);
 }
 
+void ComboBox::keyPressEvent(QKeyEvent *event)
+{
+    switch (event->key()) {
+    case Qt::Key_Enter:
+    case Qt::Key_Return:
+        emit returnPressed();
+        return;
+    }
+
+    QComboBox::keyPressEvent(event);
+}
+
 void ComboBox::wheelEvent(QWheelEvent *event)
 {
     if (!hasFocus())

src/tiled/propertyeditorwidgets.h

@@ -70,8 +70,13 @@ class ComboBox : public QComboBox
 public:
     ComboBox(QWidget *parent = nullptr);
 
+signals:
+    /** This signal is emitted when the Return or Enter key is pressed. */
+    void returnPressed();
+
 protected:
     bool event(QEvent *event) override;
+    void keyPressEvent(QKeyEvent *event) override;
     void wheelEvent(QWheelEvent *event) override;
 };
 

src/tiled/variantmapproperty.cpp

@@ -586,6 +586,10 @@ QWidget *AddValueProperty::createEditor(QWidget *parent)
         m_value = typeBox->itemData(index);
         session::propertyType = typeBox->currentText();
     });
+    connect(typeBox, &ComboBox::returnPressed, this, [this] {
+        if (!name().isEmpty())
+            emit addRequested();
+    });
 
     typeBox->installEventFilter(this);