qt5: handle Genode signals as Qt signals in QPA plugin

Fixes #3688

repos/libports/include/qt5/qpa_nitpicker/qnitpickerplatformwindow.h

@@ -96,8 +96,21 @@ class QNitpickerPlatformWindow : public QObject, public QPlatformWindow
 
 		QString _sanitize_label(QString label);
 
+		/*
+		 * Genode signals are handled as Qt signals to avoid blocking in the
+		 * Genode signal handler, which could cause nested signal handler
+		 * execution.
+		 */
+
+	private Q_SLOTS:
+
 		void _handle_input();
 		void _handle_mode_changed();
+		
+	Q_SIGNALS:
+
+		void _input();
+		void _mode_changed();
 
 	public:
 

repos/libports/lib/mk/qt5_qpa_nitpicker.mk

@@ -16,6 +16,7 @@ SRC_CC += main.cpp \
           qnitpickerintegration.cpp \
           qnitpickerplatformwindow.cpp \
           qnitpickerwindowsurface.cpp \
+          moc_qgenodeclipboard.cpp \
           moc_qnitpickerplatformwindow.cpp \
           moc_qnitpickerwindowsurface.cpp \
           moc_qnitpickerintegrationplugin.cpp

repos/libports/src/lib/qt5/qtbase/src/plugins/platforms/nitpicker/qgenodeclipboard.cpp

@@ -28,7 +28,7 @@ static constexpr bool verbose = false;
 
 
 QGenodeClipboard::QGenodeClipboard(Genode::Env &env)
-: _clipboard_signal_handler(env.ep(), *this, &QGenodeClipboard::_handle_clipboard)
+: _clipboard_signal_handler(env.ep(), *this, &QGenodeClipboard::_clipboard_changed)
 {
 	try {
 
@@ -52,6 +52,10 @@ QGenodeClipboard::QGenodeClipboard(Genode::Env &env)
 
 		}
 	} catch (...) { }
+
+	connect(this, SIGNAL(_clipboard_changed()),
+	        this, SLOT(_handle_clipboard()),
+	        Qt::QueuedConnection);
 }
 
 

repos/libports/src/lib/qt5/qtbase/src/plugins/platforms/nitpicker/qgenodeclipboard.h

@@ -28,8 +28,10 @@
 
 QT_BEGIN_NAMESPACE
 
-class QGenodeClipboard : public QPlatformClipboard
+class QGenodeClipboard : public QObject, public QPlatformClipboard
 {
+	Q_OBJECT
+
 	private:
 
 		Genode::Attached_rom_dataspace              *_clipboard_ds = nullptr;
@@ -41,8 +43,20 @@ class QGenodeClipboard : public QPlatformClipboard
 
 		QMember<QMimeData> _mimedata;
 
+		/*
+		 * Genode signals are handled as Qt signals to avoid blocking in the
+		 * Genode signal handler, which could cause nested signal handler
+		 * execution.
+		 */
+
+	private Q_SLOTS:
+
 		void _handle_clipboard();
 
+	Q_SIGNALS:
+
+		void _clipboard_changed();
+
 	public:
 
 		QGenodeClipboard(Genode::Env &env);

repos/libports/src/lib/qt5/qtbase/src/plugins/platforms/nitpicker/qnitpickerplatformwindow.cpp

@@ -509,9 +509,9 @@ QNitpickerPlatformWindow::QNitpickerPlatformWindow(Genode::Env &env, QWindow *wi
   _decoration(!window->flags().testFlag(Qt::Popup)),
   _egl_surface(EGL_NO_SURFACE),
   _input_signal_handler(_env.ep(), *this,
-                        &QNitpickerPlatformWindow::_handle_input),
+                        &QNitpickerPlatformWindow::_input),
   _mode_changed_signal_handler(_env.ep(), *this,
-                               &QNitpickerPlatformWindow::_handle_mode_changed),
+                               &QNitpickerPlatformWindow::_mode_changed),
   _touch_device(_init_touch_device())
 {
 	if (qnpw_verbose)
@@ -533,6 +533,14 @@ QNitpickerPlatformWindow::QNitpickerPlatformWindow(Genode::Env &env, QWindow *wi
 		_nitpicker_session.enqueue<Command::To_front>(_view_handle);
 		_nitpicker_session.execute();
 	}
+
+	connect(this, SIGNAL(_input()),
+	        this, SLOT(_handle_input()),
+	        Qt::QueuedConnection);
+
+	connect(this, SIGNAL(_mode_changed()),
+	        this, SLOT(_handle_mode_changed()),
+	        Qt::QueuedConnection);
 }
 
 QNitpickerPlatformWindow::~QNitpickerPlatformWindow()