- Window rules (match-by-title/class -> action), applied once when a
- matching window is first created.
--
- srd.rule(matcher, actions)
--   matcher: { title = "substring, case-insensitive", class = "exact app_id/WM_CLASS, case-insensitive" }
--            at least one of title/class is required - an empty matcher matches nothing.
--   actions: { floating = bool, maximized = bool, workspace = id,
--              x = .., y = .., width = .., height = ..,
--              decorated = bool, border_color = {r,g,b}, border_width = px }
--
- Examples:
- srd.rule({ class = "pavucontrol" }, { floating = true })
- srd.rule({ title = "picture-in-picture" }, { floating = true, width = 480, height = 270 })