diff --git a/labelme/app.py b/labelme/app.py
index 3bc8c8c38..1072d01ec 100644
--- a/labelme/app.py
+++ b/labelme/app.py
@@ -188,7 +188,7 @@ def __init__(
 
         self.canvas.newShape.connect(self.newShape)
         self.canvas.shapeMoved.connect(self.setDirty)
-        self.canvas.selectionChanged.connect(self.shapeSelectionChanged)
+        self.canvas.selectionchanged.connect(self.shapeSelectionChanged)
         self.canvas.drawingPolygon.connect(self.toggleDrawingSensitive)
 
         self.setCentralWidget(scrollArea)
diff --git a/labelme/widgets/canvas.py b/labelme/widgets/canvas.py
index 8403ea8a2..a651be42e 100644
--- a/labelme/widgets/canvas.py
+++ b/labelme/widgets/canvas.py
@@ -827,7 +827,7 @@ def offsetToCenter(self):
         aw, ah = area.width(), area.height()
         x = (aw - w) / (2 * s) if aw > w else 0
         y = (ah - h) / (2 * s) if ah > h else 0
-        return QtCore.QPointF(x, y)
+        return QtCore.QPointF(int(x), int(y))
 
     def outOfPixmap(self, p):
         w, h = self.pixmap.width(), self.pixmap.height()