I've been looking at the Display Mode choices: Linear, Hybrid, and Threaded. My observations:
In Linear mode, you see all posts to the thread, each with its post # within the thread.
In Theaded mode, you see the reply-structure (as a tree) for the thread, followed by one post. You can click a post in the tree to see that post below. Again, the post # within the thread is shown.
In Hybrid mode, you see the tree plus a number of posts below. When you click a post in the tree, the post display changes to cover only that post and its descendants. In this case, the post #s shown are within the subset, not within the whole thread. This might be misleading if you try to find the same post in the other modes.
As you switch from one mode to another, it remembers which post(s) you selected.
One last thing: In Threaded mode, there is no post reply button at the bottom, only at the top. In Linear and Hybrid mode, you get post reply buttons at the top and bottom of the display.
In Linear mode, you see all posts to the thread, each with its post # within the thread.
In Theaded mode, you see the reply-structure (as a tree) for the thread, followed by one post. You can click a post in the tree to see that post below. Again, the post # within the thread is shown.
In Hybrid mode, you see the tree plus a number of posts below. When you click a post in the tree, the post display changes to cover only that post and its descendants. In this case, the post #s shown are within the subset, not within the whole thread. This might be misleading if you try to find the same post in the other modes.
As you switch from one mode to another, it remembers which post(s) you selected.
One last thing: In Threaded mode, there is no post reply button at the bottom, only at the top. In Linear and Hybrid mode, you get post reply buttons at the top and bottom of the display.