Is there any setting which forces in folder-view to hide subtasks or better to display them nested under the main-task. At the moment I've to click every time on the categories icon to show my subtasks nested. If I don't do this it shows them with a categories icon in front as "normal task".
If you open you Filters, above your task list, you can click on Nest Subtasks. Those settings are customizable for each main View, so if you want them nested everywhere, you will have to click Nest Subtasks in each View you use.
Thanks a lot for this very fast reply. This works very good. But is there the possibility to show them toggled as a tree view? When I enable this option then I only can see the main task and it would be great to show them under this main task in a tree view.
Once subtasks are in Nested mode, they will by default be collapsed within their parent. You can open them all with the Toggle Subtasks button, or open individual parent tasks by clicking on the "subtasks" icon they have in place of the "hand icon.
No, you can't do that currently, but it has to be one of the most common requests for Toodledo, so my guess is we will be able to do that at some point. Also, someone has written a Greasemonkey script that can give you that view automatically. If you use Firefox, and are interested, it is here: https://www.toodledo.com/forums/3/2304/0/greasemonkey-firefox-script-for-auto-show-subtasks.html
Sounds nice that this will be implemented at some point. I tried your suggested Gracemonkey script, but nothing happens. Do I need special settings for Toodledo to get this working? I also tried reloading the page via CTRL+F5 which often solves problems like this with Gracemonkey.