Switch a few widgets to ui refresh modes

More closely matches native behavior on REAGL devices.
Closing those widgets should still trigger a partial refresh though,
because we usually get back to the reader, and text, so we want REAGL
;).

frontend/apps/reader/modules/readercropping.lua

@@ -73,7 +73,7 @@ end
 
 function PageCropDialog:onShow()
     UIManager:setDirty(self, function()
-        return "partial", self[1].dimen:combine(self[2].dimen)
+        return "ui", self[1].dimen:combine(self[2].dimen)
     end)
     return true
 end