Fix that files could not be dropped onto welcome screen

Needs to be implemented in Qt Quick itself nowadays.

Task-number: QTCREATORBUG-14194
Change-Id: I0456dc5d86c03672d8b6b8f9c45799851db1b059
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@theqtcompany.com>

src/plugins/welcome/welcomeplugin.cpp

@@ -52,6 +52,7 @@
 #include <QDir>
 #include <QQmlPropertyMap>
 #include <QQuickImageProvider>
+#include <QTimer>
 
 #include <QtQuickWidgets/QQuickWidget>
 #include <QtQml/QQmlContext>
@@ -135,6 +136,8 @@ public:
     QStringList recentProjectsShortcuts() const { return m_recentProjectsShortcuts; }
     QStringList sessionsShortcuts() const { return m_sessionsShortcuts; }
 
+    Q_INVOKABLE bool openDroppedFiles(const QList<QUrl> &urls);
+
 public slots:
     void setActivePlugin(int pos)
     {
@@ -307,6 +310,18 @@ void WelcomeMode::initPlugins()
     m_welcomePage->setSource(QUrl::fromLocalFile(path));
 }
 
+bool WelcomeMode::openDroppedFiles(const QList<QUrl> &urls)
+{
+    const QList<QUrl> localUrls = Utils::filtered(urls, &QUrl::isLocalFile);
+    if (!localUrls.isEmpty()) {
+        QTimer::singleShot(0, [localUrls]() {
+            ICore::openFiles(Utils::transform(localUrls, &QUrl::toLocalFile), ICore::SwitchMode);
+        });
+        return true;
+    }
+    return false;
+}
+
 void WelcomeMode::welcomePluginAdded(QObject *obj)
 {
     IWelcomePage *page = qobject_cast<IWelcomePage*>(obj);