Bug 494796

I have tenths of folders. After upgrade from 24.05.2 to 24.08.1, the folder list is not able to accomodate some reasonable amount of them, forcing me to scroll the list where I didn't need that before.

Trying to browse various settings, I cannot find anything that I could use which would have any effect on compactness (except that I can choose between three sizes of folder icons of which I've already chosen the smallest).

STEPS TO REPRODUCE
1. have a 15'' display with nice resolution (mine is 1920x1080), have some readable default font size like about 8? mm height (for other sizes, adjust the amount of subfolders in step 2 - the point is to have at least 50 items to display at once)
2. create some nice email folder structure like
folder 1
-> subfolder 1-1
-> subfolder 1-2
...
-> subfolder 1-40
folder 2
-> subfolder 2-1
...
folder 10
-> subfolder 10-1
...
-> subfolder 10-40
3. try to browse the structure in kmail

OBSERVED RESULT
you have to scroll the list up and down like insane when browsing the structure; you cannot fit more than about 30 folders at a time

EXPECTED RESULT
if you have all the folders collapsed and expand just one of them, you can see all the top folders and all the 40 subfolders of the expanded one at once, without having to scroll

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
$ kinfo
Operating System: Gentoo Linux 2.15
KDE Plasma Version: 6.1.5
KDE Frameworks Version: 6.6.0
Qt Version: 6.7.2
Kernel Version: 6.6.52-gentoo (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-4810MQ CPU @ 2.80GHz
Memory: 15.3 GiB of RAM
Graphics Processor: llvmpipe

ADDITIONAL INFORMATION