Is that intended ?
It’s intended in the parent /c/General/ but should be allowed in /c/General/general (the sub-category)
yea … just discovered that - but I was SURE I was in the sub-category … just another reason to make it more visually obvious WHERE you really are in the forum’s hierarchy.
On that point … I dont think it is intended that I can add a topic to the START-page of the whole forums … there the +Topic button is not greyed out …
No that button is available as intended. When you’re creating a new topic, regardless of where you clicked the button, it will allow you to select a category where the post will be submitted. When you click this button from the front page the category selection will not be filled in for you. The forums will then ask you to pick a category where you would like to submit your topic. 
I can only create a topic in the top section of the forum.
If i go to a subsection ( for example: issues ) i cant create a new topic.
I have to go “all categories”, click create a new topic, and select section that i want my topic to be in.
I suppose i should be able to go into that section and create a topic right there, which would automatically fill in the category flag.
How the hell can i make a new topic 
Enter one of subcategory and hit big blue button on top right side of webpage.