Update NumPy pad call for 1.17+
@@ -393,7 +393,7 @@ class Layer(KeymapMixin, ABC):
padding_needed = np.subtract(self._thumbnail_shape, thumbnail.shape)
pad_amounts = [(p // 2, (p + 1) // 2) for p in padding_needed]
- thumbnail = np.pad(thumbnail, pad_amounts)
+ thumbnail = np.pad(thumbnail, pad_amounts, mode='constant')
# blend thumbnail with opaque black background
background = np.zeros(self._thumbnail_shape, dtype=np.uint8)
