i3 dropdown terminal using your favorite terminal™️ in a special i3 container and the i3 scratchpad workspace

i3dropdown.py

#!/usr/bin/env python3
import i3ipc

DROPDOWN_IDENTIFIER       = "dropdown"
DROPDOWN_CHILD_IDENTIFIER = "dropdownchild"
INITIAL_TERMINAL_QUANTITY = 3
TERMINAL_COMMAND          = f"terminal -n {DROPDOWN_CHILD_IDENTIFIER}"
HEIGHT_PERCENTAGE         = 33

i3 = i3ipc.Connection()
tree = i3.get_tree()
focused = tree.find_focused()
workspace_rect = focused.workspace().rect

toggle_dropdown_command = f"""
  [con_mark={DROPDOWN_IDENTIFIER}] scratchpad show,
  resize set {workspace_rect.width} px {workspace_rect.height*HEIGHT_PERCENTAGE//100} px,
  move absolute position {workspace_rect.x}px {workspace_rect.y}px
"""

replies = i3.command(toggle_dropdown_command)

if all([r.success for r in replies]): exit(0)


# If we make it here, no container had the special dropdown mark.
# i3 resets marks if it gets reloaded, so search for container whose instance name is identifier
try:
  dropdown = tree.find_instanced(DROPDOWN_IDENTIFIER)[0].parent
  for r in i3.command(f'[con_id={dropdown.id}] mark --add {DROPDOWN_IDENTIFIER}'):
    print(r.error)
  print('found instance')

except IndexError:

  # Last resort, spawn a new dropdown container with our terminals

  import subprocess
  import shlex
  import json
  import tempfile

  def terminal():   # Launch a background terminal process
    subprocess.Popen( shlex.split(TERMINAL_COMMAND),
                      shell=False,
                      stdin=None,
                      stdout=None,
                      stderr=None,
                      close_fds=True )


  terminal_placeholder = {
      "border": "pixel",
      "layout": "splith",
      "current_border_width": 1,
      "floating": "auto_off",
      "percent": 0.30,
      "swallows": [{ "instance": DROPDOWN_CHILD_IDENTIFIER }]
  }

  swallowable_layout = {
      "border":   "none",
      "floating": "auto_off",
      "layout":   "splith",
      "type":     "con",
      "name":     DROPDOWN_IDENTIFIER,
      "instance": DROPDOWN_IDENTIFIER,
      "marks":    [DROPDOWN_IDENTIFIER],
      "nodes":    [terminal_placeholder] * INITIAL_TERMINAL_QUANTITY
  }

  with tempfile.NamedTemporaryFile('w', delete=True) as f:
    f.write(json.dumps(swallowable_layout))
    f.flush()
    i3.command(f'append_layout {f.name}')
  i3.command(f'[con_mark={DROPDOWN_IDENTIFIER}] move scratchpad')
  for i in range(INITIAL_TERMINAL_QUANTITY):
    terminal()

finally:
  i3.command(toggle_dropdown_command)