Refactor the way the toolbar's position is calculated for the "following" mode to make sure the toolbar:

Refactor the way the toolbar's position is calculated for the "following" mode to make sure the toolbar:

Is always visible, even when we the user selects the last or first line in the editor. (which was not the case before this commit)
To try not to overflow over the File Explorer or the Outline.

Thanks #150 @s4my