In writer you can't access a box (German: Rahmen) which is located outside the normal text margin with left mouse click. It is because of the blue line for creating a heading line.
With a right click into the box, you get the context menu. By pressing ESC key the cursor is in the box.
How to reproduce:
1. new document
2. increase the top margin
3. create a text box
4. set the anchor to side (german:Seite)
5. drag the box above the to margin
6. left mouse click into the boy -> the cursor stays where is was and you see the blue line to create a heading line
7. use the blue field an create a heading line -> now you can click into the box
You can left click into the box without creating a heading line
Operating System: Linux (Other)
Version: 18.104.22.168 release
This seems to work for me with version 4.1 RC.
In English we don't have "anchor to side" in options, we have:
1. Anchor to page
2. Anchor to paragraph
3. To Character
4. As Charactoer
1. Works fine, dragged it up to header area, clicked off of box, left clicked into box and was able to get into the text box without creating a header
4. Can't because it's a character so can't move it into header
It's a little finicky but it works if I go a little slow - if I rush it the header thing does pop up and become in the way a bit but it seems to work.
Marking as WFM - if it's still an issue for you with version 4.0 or later please mark as UNCONFIRMED and we'll investigate again.