# `window:set_config_overrides(overrides)`

*Since: 20210314-114017-04b7cedd*

Changes the set of configuration overrides for the window.
The config file is re-evaluated and any CLI overrides are
applied, followed by the keys and values from the `overrides`
parameter.

This can be used to override configuration on a per-window basis;
this is only useful for options that apply to the GUI window, such
as rendering the GUI.

Each call to `window:set_config_overrides` will emit the
[window-config-reloaded](../window-events/window-config-reloaded.md) event for
the window.  If you are calling this method from inside the handler
for `window-config-reloaded` you should take care to only call `window:set_config_overrides`
if the actual override values have changed to avoid a loop.

In this example, a key assignment (`CTRL-SHIFT-E`) is used to toggle the use of
ligatures in the current window:

```lua
local wezterm = require 'wezterm'

wezterm.on("toggle-ligature", function(window, pane)
  local overrides = window:get_config_overrides() or {}
  if not overrides.harfbuzz_features then
    -- If we haven't overriden it yet, then override with ligatures disabled
    overrides.harfbuzz_features =  {"calt=0", "clig=0", "liga=0"}
  else
    -- else we did already, and we should disable out override now
    overrides.harfbuzz_features = nil
  end
  window:set_config_overrides(overrides)
end)

return {
  keys = {
    {key="E", mods="CTRL", action=wezterm.action{EmitEvent="toggle-ligature"}},
  },
}
```

In this example, a key assignment (`CTRL-SHIFT-B`) is used to toggle opacity
for the window:

```lua
local wezterm = require 'wezterm'

wezterm.on("toggle-opacity", function(window, pane)
  local overrides = window:get_config_overrides() or {}
  if not overrides.window_background_opacity then
    overrides.window_background_opacity = 0.5;
  else
    overrides.window_background_opacity = nil
  end
  window:set_config_overrides(overrides)
end)

return {
  keys = {
    {key="B", mods="CTRL", action=wezterm.action{EmitEvent="toggle-opacity"}},
  },
}
```