Version: (using KDE KDE 3.5.6) Installed from: Ubuntu Packages If you tries to create a filter, where the Action is "Move to folder...", and that you tries to create a new folder when you Select the folder where the mail will be moved, then you could not be able to create a folder to the root folder "Local folders" (Dossiers Locaux in French). I hope this explanation was quite clear, and I've provided a screenshot.
Created attachment 19589 [details] The "New sub-folder" button stays disabled while "Local folders" is selected
I can confirm this with KMail 1.9.6. Additionally, the first click on "Local Folders" does not disable the "New sub-folder" button, as it probably should.
*** This bug has been marked as a duplicate of 128796 ***