Center AwesomeWM floating windows when created and toggled.

center-awesome-floating.lua

-- This file includes both changes that need to be made, but they likely won't be placed like this in your files.
-- You will need to find the place to include those lines. You can ask me if you can't figure it out.

-- -- -- -- -- -- -- -- -- -- -- -- -- -- --
-- Key to toggle between floating and tiled

clientkeys = gears.table.join( -- Find by this line
awful.key({modkey, "Control"}, "space", function(c) -- Center and raise floating windows if there is more than one
  awful.client.floating.toggle(c)
  local num_tiled_clients = 0
  for _ in pairs(c.screen.tiled_clients) do num_tiled_clients = num_tiled_clients + 1 end
  if num_tiled_clients >= 1 then
    awful.placement.centered(c, nil)
  end
  c:raise()
end,
{
  description = "Toggle floating",
  group = "client"
}
),
)

-- -- -- -- -- -- -- -- -- -- -- -- -- -- --
-- This way you set the default behaviour

awful.rules.rules = {{ -- All clients will match this rule.
    rule = {},
    properties = {
        border_width = beautiful.border_width,
        border_color = beautiful.border_normal,
        focus = awful.client.focus.filter,
        raise = true,
        keys = clientkeys,
        buttons = clientbuttons,
        screen = awful.screen.preferred,
        titlebars_enabled = false,
        placement = awful.placement.centered + awful.placement.no_overlap + awful.placement.no_offscreen -- This is the important line
    }
},