Folders cannot be sorted by size

[Flavescent]

Describe the bug If folder sizes are displayed in the "Size" column, they cannot be sorted by.

To Reproduce Steps to reproduce the behavior:

1. Enable option Tools > Options > Files and Folders > Show folder sizes
2. Open a directory with folders in it
3. Click on the "Size" column to sort by size
4. The folders are instead sorted alphabetically

Expected behavior Folders should be sorted by size.

Version (please complete the following information):

• Explorer++ version: 1.4.0.1748 beta (64-bit build)
• OS: Windows 10

Comments This error does not occur in version 1.3.5.

[sean-e]

see also issue #239