In M-x term, try:

  $ seq 100
  $ htop
  Press 'q' to exit htop.

(Instead of 'htop', you could also try with 'emacs -q', 'vi' or any
other full-screen TUI program.)

Current behaviour: htop overwrites a portion of output from the 'seq'
command and htop's contents remain visible on the screen after pressing
'q'.

Proposed behaviour (patch attached): avoid overwriting output from the
'seq' command and erase htop's contents after exiting. This is the
default behaviour of xterm, st and most other terminal emulators.

Best regards.