Hey :)
I did something like this last fall, because we had the same problem with clicking through the folders.
The GUI for the folder loading looks different then the GUI for file loading. I did this because i found this stack overflow conversation, where they describe how to select multiple folders with a non native interface
Load multiple folders dialog
standart dialog for loading files
I could do a pull request for this on github. Till now i hesitated, because the interface is non-native. I have only tested this on a windows system.