Set and unset individual atoms in _NET_WM_STATE instead of overwriting the entire list everytime. This allows independent management of multiple states.

fixes #1873

src/xcb.c

@@ -274,3 +274,48 @@ xcb_visualid_t get_visualid_by_depth(uint16_t depth) {
     }
     return 0;
 }
+
+/*
+ * Add an atom to a list of atoms the given property defines.
+ * This is useful, for example, for manipulating _NET_WM_STATE.
+ *
+ */
+void xcb_add_property_atom(xcb_connection_t *conn, xcb_window_t window, xcb_atom_t property, xcb_atom_t atom) {
+    xcb_change_property(conn, XCB_PROP_MODE_APPEND, window, property, XCB_ATOM_ATOM, 32, 1, (uint32_t[]){atom});
+}
+
+/*
+ * Remove an atom from a list of atoms the given property defines without
+ * removing any other potentially set atoms.  This is useful, for example, for
+ * manipulating _NET_WM_STATE.
+ *
+ */
+void xcb_remove_property_atom(xcb_connection_t *conn, xcb_window_t window, xcb_atom_t property, xcb_atom_t atom) {
+    xcb_grab_server(conn);
+
+    xcb_get_property_reply_t *reply =
+        xcb_get_property_reply(conn,
+                               xcb_get_property(conn, false, window, property, XCB_GET_PROPERTY_TYPE_ANY, 0, 4096), NULL);
+    if (reply == NULL || xcb_get_property_value_length(reply) == 0)
+        goto release_grab;
+    xcb_atom_t *atoms = xcb_get_property_value(reply);
+    if (atoms == NULL) {
+        goto release_grab;
+    }
+
+    {
+        int num = 0;
+        const int current_size = xcb_get_property_value_length(reply) / (reply->format / 8);
+        xcb_atom_t values[current_size];
+        for (int i = 0; i < current_size; i++) {
+            if (atoms[i] != atom)
+                values[num++] = atoms[i];
+        }
+
+        xcb_change_property(conn, XCB_PROP_MODE_REPLACE, window, property, XCB_ATOM_ATOM, 32, num, values);
+    }
+
+release_grab:
+    FREE(reply);
+    xcb_ungrab_server(conn);
+}