+-------------------+           +------------------+        +------------------+         +--------------+
  |  session          |    +------|  winlink         |     +--| window           |      +--| layout_cell  |---+
  |-------------------|    |      |------------------|     |  | --------------   |      |  | ------------ |   |
  |  - idx            |    |      |  - idx           |     |  | - name           |      |  | - type       |   |
  |  - name           |    |      |  - window  @-----------+  | - name_timer     |      +----@ parent     |   |
  |  - cwd            |    |      |  - status_width  |        | - silence_timer  |         | - sx, sy     |   |
  |  - creation time  |    |      |  - status_cell   |     +----@ active         |         | - xoff, yoff |   |
  |  - activity time  |    |      |  - status_text   |     |.---@ last           |       +---@ wp         |   |
  |  - sx, sy         |    |      |  - flags         |     |.---O panes          |       | | - cells O--------+
  |  - curw    @----------'|      +------------------+     |  | - lastlayout     |       | +--------------+
  |  - lastw   O----------'|                               |  | - layout_root @----------)--'   |
  |  - windows O-----------+                               |  | - sx, sy         |       |      |
  |  - options @---------------+            ;------+       |  | - flags          |       |      |
  |  - flags          |        |   +-----------+   |   ,---)--+-@ options        |       |      |
  |  - tio            |        +---| options   |---)---'   |  | - references     |       |      |
  |  - environ        |            |-----------|   |       |  +------------------+       |      |
  |  - wlmouse        |        +-----O tree    |   |       |          |                  |      |
  |  - references     |        |   | - parent @----+       |          |                  |      |
  +-------------------+        |   +-----------+           |          |                  |      |
    |                          |                           |          |                  |      |
    |                          |                           |          |                  |      |
+---+                          |                           |          |                  |      |
|                              |  +---------------+        |          |   +----------------+    |
| +----------------+           +--| options_entry |        +-------+--)---| window_pane    |    |
| | session_group  |              | ------------- |                |  |   | ------------   |    |
| | -------------  |              | - name        |                |  |   | - id           |    |
+---O sessions     |              | - type        |                |  +-----@ window       |    |
  +----------------+              | - str         |                |      | - layout_cell @-----+
                                  | - num         |                |      | - sx, sy       |
                                  | - data        |                |      | - xoff, yoff   |
                                  +---------------+                |      | - flags        |
                                                                   |      | - cmd          |         +-------------+
                                         +-------------------------+---+  | - pid          |         | window_mode |
           +------------------+          |                         |   |  | - tty          |         | ----------- |
           | screen           |----------+    +------------------+ |   |  | - fd           |         | - init()    |
           |------------------|               | input_ctx        | |   |  | - event        |         | - free()    |
           | - title          |               |------------------|-)---)----@ ictx         |         | - resize()  |
       +-----@ grid           |               | - wp @-----------+-+   |  | - pipe_fd      |         | - key()     |
       |   | - cx, cy         |     +-----------@ ctx            |     |  | - pipe_event   |         | - mouse()   |
       |   | - rupper, rlower |     |     +-----@ cell           |     |  | - pipe_off     |         | - timer()   |
       |   | - mode           |     |     |   | - old_cx, old_cy |     |`---@ screen       |         +-------------+
       |   | - tabs           |     |     |   | - interm_buf,len |     +----@ base         |           |
       |   | - sel @---+      |     |     |   | - param_buf,len  |        | - saved_cx     |           |
       |   +-----------|------+     |     |   | - input_buf,len  |        | - saved_cy     |           |
       |    |          |            |     |   | - param_list,len |     +----@ saved_grid   |           |
       |    |          |            |     |   | - utf8data       |     |  | - saved_cell @--------+    |
       |    |    +------------+     |     |   | - ch             |     |  | - mode @-------+------)----+
       |    |    | screen_sel |     |     |   | - flags          |     |  | - modedata     |      |
       |    |    | ---------- |     |     |   | - state          |     |  +----------------+      |
       |    |    | - flag     |     |     |   +------------------+     |     |                    |
       |    |    | - rectflag |     |     |           +----------------+     |                    |
       |    |    | - sx       |     |     |           |                      |                +------------+
       |    |    | - sy       |     |     +-----------)----------------------)----------------| grid_cell  |
       |    |    | - ex       |     |                 |                      |                |------------|
       |    |    | - ey       |     | +---------------)----------------------+                | - attr     |
       |    |    | - cell     |     | |               |                                       | - flags    |
       |    |    +------------+     | |     +------------+                                    | - fg       |
       |    |                       | |     | grid       |            +------------+          | - bg       |
       |    |                    +--+ |     |------------|     +------| grid_line  |          | - data     |
       |    |                    |    |     | - flags    |     |      | ---------- |          +------------+
       |    |  +------------------+   |     | - sx, sy   |     |      | - cellsize |           |
       |    |  | screen_write_ctx |   |     | - hsize    |     |      | - celldata O-----------+
       |    |  | ---------------- |   |     | - hlimit   |     |      | - utf8size |
       |    |  | - wp @---------------+     | - linedata @-----+      | - utf8data O-------+
       |    +----@ s              |         +------------+            | - flags    |       |   +-----------+
       |       +------------------+           |                       +------------+       +---| grid_utf8 |
       |                                      |                                                |-----------|
       +--------------------------------------+                                                | - width   |
                                                                                               | - data    |
                                                                                               +-----------+



--------------------------------------------------------------------------------------------------------------
A higher level view of the same:

                ,-------------------------------------.
           ,----|               client                |
           |    | Represents a connected tmux client. |<<--[clients global array, may have null pointers]
           |    | tmux client.                        |
           |    |                                     |
           |    |   ,------------------------------.  |
           |    |   |      tty                     |  |
           |    |   | Info about client's display. |  |
           |    |   `------------------------------'  |
           |    `----.--------------------------------'
           |         |
           |         |
           |         V
           |    ,-----------------------------------.
           |    |             session               |<<--[sessions global array]
           |    | All that a single client may see. |
           |    | termios                           |
           |    `----.------------------------------'
           |         |
           |         V
           |         V
           |     .---------------------.          ,------------------.
           |     |       window        |.         |   layout_cell    |.
           |     | Full-screen view.   |-------->>|                  ||
           |     `----.----------------'|    ,-->>| Describes panes. ||
           |       `--|-----------------'    |    `------------------'|
           |          |                      |     `------------------'
           |          |   ,------------------'
           |          |   |
           |          |   |   ,---------------------------------.
           |          V   |   |                                 |
           |          V   |   V                                 |
           |        .-------'-----.       ,-----------.      ,-------------------.
           |        | window_pane |<<---->| input_ctx |----->| screen_write_ctx  |
           |        |             ||      |           |      |                   |
           |        | One child.  ||      | State for |      | Joins window_pane |
           |        | tty, fd,    ||      | parsing   |      | and screen.       |
           |        | etc.        ||      | input     |      |                   |
           |        `-.-----------'|      `-----------'      `--.----------------'
           |         `|------------'                            |
           |          |                                         |
           |          | ,---------------------------------------'
           |          | |
           |          V V
           |     ,------------------.           ,--------------.      ,----------.       ,---------.
           `---->|     screen       |---------->|    grid      |----->|grid_lines|------>|grid_cell|
                 | Backing store of |           | Screen chars.|      `----------'       `---------'
                 | screen contents. |           | Screen size. |
                 | Cursor pos'n.    |           `--------------'
                 | Scroll region.   |
                 `------------------'