The contract shared by the pz_act_*() functions.
Acting on the page
The pz_act_*() functions use the page the way a person would. They send
real browser input, such as pointer moves, clicks and key presses, or use
the browser's own focus and text-selection methods. They never set a form
value directly.
An action with a target looks for it in the current scope and waits until
it matches an element. Inside a scope, target = NULL acts on the scope's
element, and scrolling with by or to scrolls the scope's container. An
explicit target is scrolled into view first when needed. A few actions,
like pz_act_press(), take no target and act on the focused element
instead.
While the page is recording, actions are staged as pz_stage() sets them
up: the cursor glides to pointer targets, typing is paced, scrolls normally
use the mouse wheel, and the page holds for the staged pause afterward.
Without a recording, actions go straight to their final state.
To set a value directly instead, without staging, use pz_set_value(),
pz_set_files(), or pz_set_shiny_input().