various fixes

masque/traits/positionable.py

@@ -94,7 +94,7 @@ class PositionableImpl(Positionable, metaclass=ABCMeta):
 
     @offset.setter
     def offset(self, val: vector2):
-        if not isinstance(val, numpy.ndarray):
+        if not isinstance(val, numpy.ndarray) or val.dtype != numpy.float64:
             val = numpy.array(val, dtype=float)
 
         if val.size != 2:
@@ -109,7 +109,6 @@ class PositionableImpl(Positionable, metaclass=ABCMeta):
         self.offset = offset
         return self
 
-
     def translate(self: I, offset: vector2) -> I:
         self._offset += offset
         return self

masque/traits/rotatable.py

@@ -109,6 +109,7 @@ class PivotableImpl(Pivotable, metaclass=ABCMeta):
     """
     __slots__ = ()
 
+    @abstractmethod
     def rotate_around(self: J, pivot: vector2, rotation: float) -> J:
         pivot = numpy.array(pivot, dtype=float)
         self.translate(-pivot)