[imp] IMP Folders list

[zBit]

Hello,
I cannot find any option nor preference for DIMP handling the way all folders are grouped and sorted in sidebar menu. I can see one group of system folders like inbox, drafts and sent, then some applications like Turba and finally the group of user-created folders. That way some users have inbox twice (the system one that is clickable and the other one among the user-defined folders) which is a little confusing. Is there a way to setup folders abreast so that all folders would shown in one group altogether?

I am using the clean pear installation of stable release (IMP 5.0.18) in order to refrain from possible messed configuration. I have checked through the original prefs.php and conf.php files but still have no clue of how to manage this thing.

----
inbox
drafts
sent
----
turba
----
inbox
-folder1
-folderX
another-folder
-folderY
- -folderXY
- - -etc

Thanks for any tip, David