Fixed a bug when application crashes on polygon deletion. Closes #556

labelme/widgets/canvas.py

@@ -222,7 +222,6 @@ class Canvas(QtWidgets.QWidget):
             return
 
         # Polygon/Vertex moving.
-        self.movingShape = False
         if QtCore.Qt.LeftButton & ev.buttons():
             if self.selectedVertex():
                 self.boundedMoveVertex(pos)
@@ -364,6 +363,7 @@ class Canvas(QtWidgets.QWidget):
                 self.repaint()
         elif ev.button() == QtCore.Qt.LeftButton and self.selectedShapes:
             self.overrideCursor(CURSOR_GRAB)
+
         if self.movingShape and self.hShape:
             index = self.shapes.index(self.hShape)
             if (self.shapesBackups[-1][index].points !=
@@ -371,6 +371,8 @@ class Canvas(QtWidgets.QWidget):
                 self.storeShapes()
                 self.shapeMoved.emit()
 
+            self.movingShape = False
+
     def endMove(self, copy):
         assert self.selectedShapes and self.selectedShapesCopy
         assert len(self.selectedShapesCopy) == len(self.selectedShapes)