I've got a lot of cases where I'd like to be able to see two terminal contents concurrently to compare or copy or various other reasons. gnome-terminal supports tabs, and you can detach/reattach tabs between windows, but it would be nice if it natively supported horizontal and vertical splitting.

What I'm picturing borders on adding basic titling window management logic to gnome-terminal, so I won't be too offended if you close as WONT_FIX, but I really think it would make this use case much simpler if gnome-terminal were dealing with the titling instead of relying on multiple windows and the window manager to arrange them. It will become a more automatic process, window alignment will be better, and it would become easier to shift things around and rearrange. Shortcut keys can be added specifically for moving to a different tab region.

Different arrangements:
+-----+
|t|t|t|
+-----+
| 1   |
+-----+

+-----+-----+
|t|t|t|t|t|t|
+-----+-----+
| 1   | 2   |
+-----+-----+

+-----+
|t|t|t|
+-----+
| 1   |
+-----+
|t|t|t|
+-----+
| 2   |
+-----+

+-----+-----+
|t|t|t|t|t|t|
+-----+-----+
| 1   | 3   |
+-----+     |
|t|t|t|     |
+-----+     |
| 2   |     |
+-----+-----+

+-----+-----+
|t|t|t|t|t|t|
+-----+-----+
| 1   | 2   |
|     +-----+
|     |t|t|t|
|     +-----+
|     | 3   |
+-----+-----+


+-----+-----+
|t|t|t|t|t|t|
+-----+-----+
| 1   | 2   |
+-----+-----+
|t|t|t|t|t|t|
+-----+-----+
| 3   | 4   |
+-----+-----+

Basically allow up to for sections of the gnome-terminal instance that the GtkNotebook can by dragged between. Allow the boundary between the sections to be dragged to resize too.