After the last update (no version in the about) i've lost all my folders.
I can get the folder config via the settings dialog - but I can not restore the
settings.
Is it possible to get a feature like this?

Thanks

Bart

Generally I think a backup & restore function is a good idea, thinking of
something along these lines  (last known good folders would be also a nice
version of that) for QF 3.0.

The folder string can be restored manually to about:config, 

open Tools / Options / Advanced > General Tab and click on [Config editor]

set the filter to "QuickFolders.folders"  (without quotation marks)

Paste the string, click ok and restart thunderbird. Please note that you might
have bug 24451, which you need to fix before you can restore the folders.
Simply install version 2.9.1, it has been released today.

Definitely an important feature that is to come on or before version 4.0!

Created an attachment (id=8626) [details]
4.15.1 prerelease 15

(minified version - all locales removed except English and German)

the "QuickFolders Pro" tab now has an option to "Save Configuration" / "Load
Configuration". note that this will currently only save / load Tabs, the other
settings pointed to in the checkboxes below (general / advanced / layout) need
yet to be implemented.

Created an attachment (id=8627) [details]
4.15.1 prerelease 36

Load: Includes options for tabs, general, advand+layout settings.
Store: always stores everything.

Note: at the moment, the license key is not part of the configuration (I am
still considering whether it is necessary as part of the configuration)

This version only has English & German locale for testing.

Created an attachment (id=8632) [details]
4.15.1 prerelease 50

Added ability to restore tabs and categories even if folders do not exist.
These can be removed using the 'Find orphaned tabs' command on tool menu (blue
cogwheel)

Created an attachment (id=8633) [details]
4.15.1 prerelease 59

Added some stability in case invalid tabs are loaded. Also streamlined the
"find orphaned tabs" function by adding an option to answer remaining questions
about deleting an invalid folder with Yet / No.

Created an attachment (id=8634) [details]
4.15.1 prerelease 88

This version deals better with invalid folder URIs which can happen when we
import a backup from an old profile (the folder was deleted or moved on the
profile in the meantime).

it will still load (and display) the tabs of non-existent folders but show them
with a "broom" icon and a tooltip to use "Find orphaned tab" to delete them.
They can be right-clicked for getting the QuiockFolders command menu. A normal
left-click on such an invalid tab offers to delete the tab.

note: this can also happen if a mail account has a different username when it
is set up on a different PC; the first pickeed username must match for the
folder URIs to be recognized on both systems. It is likely that renaming an
existing mail account will _NOT_ remedy this problem.

released in 4.15.1, 04/06/2019