Comment 5 for bug 1922276

The "Select All" shortcut, when enabled, only selects text from the end of the buffer that fits precisely within the height of the terminal.

For example

1. Type `ls -l /lib/*` and press Enter.
2. Scroll the terminal to the beginning.
3. Select all using your configured shortcut (Ctrl-Shift-A in my case).
4. Notice that no text is selected.
5. Then scroll the terminal to the bottom.
6. Notice all of the text that fits within the terminal window size is selected.
7. You can expand the terminal vertically to see that text above this area is not selected.