As far as I remember Google group discussions I'm not the only dreaming about this feature. So, the aim is to calculate total files' size only, omitting directories nodes (taking at my system at most case 4096 bytes each). It can be as main and the only way or another command or checkbox option - any way would be appreciated!
Sorry, I forgot about this topic. You're right: This is a matter of what the users expect: size of all files vs. size of files and directories ON FILESYSTEM. However, the new behaviour is caused by switching to KDE KIO for the calculation. This makes the values equal to the right-click->Properties page size. The new behaviour must be added there now. (BTW: I inserted a cache for the calculated directory sizes, but they are not automatically updated on changes.)
Yes, I have noticed that cache, and I guess it is acceptable to not be auto-updated (at least by default) as far as it potentially can take noticeable IO resources.
(Coming from Bug 379170) Both options - counting the size of directories itself or not - can be totally valid. The old behaviour was omitting directories and I guess I have to restore this. Right now the "Size" column already shows "0 B" for empty directories.
As Alex is no longer an active dev, resetting assignee to default, so others could take it.