Fix regression caused by use of _new_book in USBMS

src/calibre/devices/usbms/driver.py

@@ -298,6 +298,7 @@ class USBMS(CLI, Device):
         # Clear the _new_book indication, as we are supposed to be done with
         # adding books at this point
         for blist in booklists:
+            if blist is not None:
                 for book in blist:
                     book._new_book = False
 

src/calibre/gui2/widgets.py

@@ -148,8 +148,8 @@ class FormatList(QListWidget):
 
 class ImageView(QLabel):
 
-    MAX_WIDTH  = 400
-    MAX_HEIGHT = 300
+    MAX_WIDTH  = 600
+    MAX_HEIGHT = 800
     DROPABBLE_EXTENSIONS = IMAGE_EXTENSIONS
 
     @classmethod