Change remove button signal emission to new style signals.

openlp/plugins/songs/forms/duplicatesongremovalform.py

@@ -331,9 +331,7 @@ class DuplicateSongRemovalForm(OpenLPWizard):
             self.songs_horizontal_layout.addStretch()
             for duplicate in self.duplicate_song_list[-1]:
                 song_review_widget = SongReviewWidget(self.review_page, duplicate)
-                QtCore.QObject.connect(song_review_widget,
+                song_review_widget.song_remove_button_clicked.connect(self.remove_button_clicked)
-                        QtCore.SIGNAL(u'song_remove_button_clicked(PyQt_PyObject)'),
-                        self.remove_button_clicked)
                 self.songs_horizontal_layout.addWidget(song_review_widget)
             self.songs_horizontal_layout.addStretch()
             self.songs_horizontal_layout.addStretch()

openlp/plugins/songs/forms/songreviewwidget.py

@@ -42,6 +42,18 @@ class SongReviewWidget(QtGui.QWidget):
     The remove logic is not implemented here, but a signal is provided
     when the remove button is clicked.
     """
+
+    # Signals have to be class variables and not instance variables. Otherwise
+    # they are not registered by Qt (missing emit and connect methods are artifacts of this).
+    # To use SongReviewWidget as a signal parameter one would have to assigning the class
+    # variable after the class is declared. While this is possible, it also messes Qts meta
+    # object system up. The result is an
+    # "Object::connect: Use the SIGNAL macro to bind SongReviewWidget::(QWidget*)" error on
+    # connect calls.
+    # That's why we cheat a little and use QWidget instead of SongReviewWidget as parameter.
+    # While not being entirely correct, it does work.
+    song_remove_button_clicked = QtCore.pyqtSignal(QtGui.QWidget)
+
     def __init__(self, parent, song):
         """
         ``parent``
@@ -168,4 +180,4 @@ class SongReviewWidget(QtGui.QWidget):
         """
         Signal emitted when the "remove" button is clicked.
         """
-        self.emit(QtCore.SIGNAL(u'song_remove_button_clicked(PyQt_PyObject)'), self)
+        self.song_remove_button_clicked.emit(self)