contrib: add a keyboard layout per window script

Fixes https://github.com/swaywm/sway/issues/2361

contrib/keyboard-layout-per-window.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python
+
+# This script keeps track of active keyboard layouts per window.
+#
+# This script requires i3ipc-python package (install it from a system package
+# manager or pip).
+
+import i3ipc
+
+ipc = i3ipc.Connection()
+prev_focused = -1
+windows = {}
+
+def on_window_focus(ipc, event):
+    global windows, prev_focused
+
+    # Save current layout
+    layouts = {}
+    for input in ipc.get_inputs():
+        layouts[input.identifier] = input.xkb_active_layout_index
+    windows[prev_focused] = layouts
+
+    # Restore layout of the newly focused window
+    if event.container.id in windows:
+        for (input_id, layout_index) in windows[event.container.id].items():
+            if layout_index != layouts[input_id]:
+                ipc.command("input \"{}\" xkb_switch_layout {}".format(
+                    input_id, layout_index))
+
+    prev_focused = event.container.id
+
+def on_window_close(ipc, event):
+    global windows
+    if event.container.id in windows:
+        del(windows[event.container.id])
+
+def on_window(ipc, event):
+    if event.change == "focus":
+        on_window_focus(ipc, event)
+    elif event.change == "close":
+        on_window_close(ipc, event)
+
+ipc.on("window", on_window)
+ipc.main()