Adhere to ICCCM focus specification

For certain applications (e.g. JetBrains) the parent window controls
input. We need to adhere to the ICCCM input focus specification to
properly handle these cases.

Relates to swaywm/wlroots#2604

sway/tree/view.c

@@ -785,7 +785,18 @@ void view_map(struct sway_view *view, struct wlr_surface *wlr_surface,
 
 	view_execute_criteria(view);
 
-	if (should_focus(view)) {
+	bool set_focus = should_focus(view);
+
+#if HAVE_XWAYLAND
+	if (wlr_surface_is_xwayland_surface(wlr_surface)) {
+		struct wlr_xwayland_surface *xsurface =
+			wlr_xwayland_surface_from_wlr_surface(wlr_surface);
+    	set_focus = (wlr_xwayland_icccm_input_model(xsurface) !=
+			WLR_ICCCM_INPUT_MODEL_NONE) && set_focus;
+	}
+#endif
+
+	if (set_focus) {
 		input_manager_set_focus(&view->container->node);
 	}