fix(bspwm): Restack against topmost root window.

The ewmh strategy has to be dropped because the
`_NET_SUPPORTING_WM_CHECK` window may (at least in bspwm) appear
anywhere in the window stack.

To fix the overlapping monitors issue in #2873, we simply restack
against the topmost of these root windows.

Fixes #2972
Fixes #2873 (again)

CHANGELOG.md

@@ -52,7 +52,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Changed fuzzy match option on i3 and bspwm modules to find longest match instead of the first match ([`#2831`](https://github.com/polybar/polybar/pull/2831), [`#2829`](https://github.com/polybar/polybar/issues/2829)) by [@Ron0Studios](https://github.com/ron0studios/).
 - `wm-restack`
   - `generic`: Is now a best effort combination of other restacking strategies. First tries `ewmh` and then the `bottom` strategy ([`#2961`](https://github.com/polybar/polybar/pull/2961))
-  - `bspwm`: First tries the `ewmh` strategy before falling back to its old behavior ([`#2961`](https://github.com/polybar/polybar/pull/2961))
+  - `bspwm`: Will restack above the topmost bspwm root window instead of the root window associated with the monitor polybar is on ([`#3019`](https://github.com/polybar/polybar/pull/3019))
 
 ### Fixed
 - Waiting for double click interval on modules that don't have a double click action ([`#2663`](https://github.com/polybar/polybar/issues/2663), [`#2695`](https://github.com/polybar/polybar/pull/2695))

include/utils/bspwm.hpp

@@ -1,38 +1,30 @@
 #pragma once
 
-#include <xcb/xcb.h>
-#include <xcb/xcb_icccm.h>
-
 #include "common.hpp"
-#include "settings.hpp"
 #include "utils/restack.hpp"
 #include "utils/socket.hpp"
-#include "utils/string.hpp"
-#include "x11/extensions/randr.hpp"
-#include "x11/window.hpp"
 
 POLYBAR_NS
 
 class connection;
 
 namespace bspwm_util {
-  struct payload;
-  using connection_t = unique_ptr<socket_util::unix_connection>;
-  using payload_t = unique_ptr<payload>;
+using connection_t = unique_ptr<socket_util::unix_connection>;
 
-  struct payload {
-    char data[BUFSIZ]{'\0'};
-    size_t len = 0;
-  };
+struct payload {
+  char data[BUFSIZ]{'\0'};
+  size_t len = 0;
+};
 
-  vector<xcb_window_t> root_windows(connection& conn);
-  restack_util::params get_restack_params(connection& conn, const monitor_t& mon, xcb_window_t bar_window);
+using payload_t = unique_ptr<payload>;
 
-  string get_socket_path();
+restack_util::params get_restack_params(connection& conn);
 
-  payload_t make_payload(const string& cmd);
-  connection_t make_connection();
-  connection_t make_subscriber();
-}
+string get_socket_path();
+
+payload_t make_payload(const string& cmd);
+connection_t make_connection();
+connection_t make_subscriber();
+} // namespace bspwm_util
 
 POLYBAR_NS_END

src/components/bar.cpp

@@ -506,7 +506,7 @@ void bar::restack_window() {
   } else if (wm_restack == "bottom") {
     restack_params = restack_util::get_bottom_params(m_connection, bar_window);
   } else if (wm_restack == "bspwm") {
-    restack_params = bspwm_util::get_restack_params(m_connection, m_opts.monitor, bar_window);
+    restack_params = bspwm_util::get_restack_params(m_connection);
 #if ENABLE_I3
   } else if (wm_restack == "i3" && m_opts.override_redirect) {
     restack_params = i3_util::get_restack_params(m_connection);

src/utils/bspwm.cpp

@@ -1,64 +1,41 @@
 #include "utils/bspwm.hpp"
 
 #include <sys/un.h>
+#include <xcb/xcb.h>
 
 #include "errors.hpp"
 #include "utils/env.hpp"
+#include "utils/string.hpp"
 #include "x11/connection.hpp"
-#include "x11/ewmh.hpp"
+#include "x11/icccm.hpp"
 
 POLYBAR_NS
 
 namespace bspwm_util {
 /**
- * Get all bspwm root windows
+ * Returns window against which to restack.
+ *
+ * Bspwm creates one root window per monitor with a `WM_CLASS` value of `root\0Bspwm` and the window taking up the
+ * entire monitor.
+ * For overlapping monitors, stacking polybar above the root window for its monitor, but below the root window for an
+ * overlapping monitor, may cause the upper root window to obstruct polybar, at least in terms of receiving mouse
+ * clicks. Because of that, we simply restack polybar above the topmost root window.
  */
-vector<xcb_window_t> root_windows(connection& conn) {
-  vector<xcb_window_t> roots;
+restack_util::params get_restack_params(connection& conn) {
   auto children = conn.query_tree(conn.root()).children();
 
-  for (auto it = children.begin(); it != children.end(); it++) {
-    xcb_icccm_get_wm_class_reply_t reply{};
-    reply.class_name = reply.instance_name = nullptr;
+  xcb_window_t top_root = XCB_NONE;
 
-    if (xcb_icccm_get_wm_class_reply(conn, xcb_icccm_get_wm_class(conn, *it), &reply, nullptr)) {
-      if (string_util::compare("Bspwm", reply.class_name) && string_util::compare("root", reply.instance_name)) {
-        roots.emplace_back(*it);
-      }
-    }
+  // Iteration happens from bottom to top
+  for (xcb_window_t wid : children) {
+    auto [instance_name, class_name] = icccm_util::get_wm_class(conn, wid);
 
-    if (reply.class_name != nullptr || reply.instance_name != nullptr) {
-      xcb_icccm_get_wm_class_reply_wipe(&reply);
+    if (string_util::compare("root", instance_name) && string_util::compare("Bspwm", class_name)) {
+      top_root = wid;
     }
   }
 
-  return roots;
-}
-
-/**
- * Returns window against which to restack.
- */
-restack_util::params get_restack_params(connection& conn, const monitor_t& mon, xcb_window_t bar_window) {
-  auto ewmh_params = restack_util::get_ewmh_params(conn);
-
-  if (restack_util::are_siblings(conn, bar_window, ewmh_params.first)) {
-    return ewmh_params;
-  }
-
-  for (auto&& root : root_windows(conn)) {
-    auto geom = conn.get_geometry(root);
-
-    if (mon->x != geom->x || mon->y != geom->y) {
-      continue;
-    }
-    if (mon->w != geom->width || mon->h != geom->height) {
-      continue;
-    }
-
-    return {root, XCB_STACK_MODE_ABOVE};
-  }
-
-  return restack_util::NONE_PARAMS;
+  return {top_root, XCB_STACK_MODE_ABOVE};
 }
 
 /**