fix: Set WM_SIZE_HINTS to fix position in openbox

When polybar is remapped (either through IPC or something like xdo
show), openbox positions it somewhere on the screen using the same
positioning algorithm as it would for regular windows.

If the position and size is set in the WM_SIZE_HINTS atom, openbox will
respect the position and size declared by the window.

Fixes #2021

CHANGELOG.md

@@ -222,6 +222,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `internal/battery`: More accurate battery state
 ([`#2563`](https://github.com/polybar/polybar/issues/2563))
 - Some modules stop updating when system time moves backwards. ([`#857`](https://github.com/polybar/polybar/issues/857), [`#1932`](https://github.com/polybar/polybar/issues/1932))
+- Broken positioning in Openbox when the bar is hidden and shown again
+  ([`#2021`](https://github.com/polybar/polybar/issues/2021))
 
 ## [3.5.7] - 2021-09-21
 ### Fixed

include/x11/icccm.hpp

@@ -13,6 +13,8 @@ namespace icccm_util {
   void set_wm_name(xcb_connection_t* c, xcb_window_t w, const char* wmname, size_t l, const char* wmclass, size_t l2);
   void set_wm_protocols(xcb_connection_t* c, xcb_window_t w, vector<xcb_atom_t> flags);
   bool get_wm_urgency(xcb_connection_t* c, xcb_window_t w);
+
+  void set_wm_size_hints(xcb_connection_t* c, xcb_window_t w, int x, int y, int width, int height);
 }
 
 POLYBAR_NS_END

src/components/bar.cpp

@@ -593,6 +593,8 @@ void bar::reconfigure_wm_hints() {
 
   m_log.trace("bar: Set window _NET_WM_PID");
   ewmh_util::set_wm_pid(win);
+
+  icccm_util::set_wm_size_hints(m_connection, win, m_opts.pos.x, m_opts.pos.y, m_opts.size.w, m_opts.size.h);
 }
 
 /**
@@ -872,9 +874,6 @@ void bar::start() {
   // Notify all components that depend on the absolute bar position (such as the background manager).
   m_sig.emit(signals::ui::update_geometry{});
 
-  // Reconfigure window position after mapping (required by Openbox)
-  reconfigure_pos();
-
   m_log.trace("bar: Draw empty bar");
   m_renderer->begin(m_opts.inner_area());
   m_renderer->end();

src/x11/icccm.cpp

@@ -38,6 +38,18 @@ namespace icccm_util {
     }
     return false;
   }
+
+  void set_wm_size_hints(xcb_connection_t* c, xcb_window_t w, int x, int y, int width, int height) {
+    xcb_size_hints_t hints;
+
+    xcb_icccm_size_hints_set_size(&hints, false, width, height);
+    xcb_icccm_size_hints_set_min_size(&hints, width, height);
+    xcb_icccm_size_hints_set_max_size(&hints, width, height);
+    xcb_icccm_size_hints_set_base_size(&hints, width, height);
+    xcb_icccm_size_hints_set_position(&hints, false, x, y);
+
+    xcb_icccm_set_wm_size_hints(c, w, XCB_ATOM_WM_NORMAL_HINTS, &hints);
+  }
 }
 
 POLYBAR_NS_END