X11: Fix updating GLFW_FLOATING on a hidden window

README.md

@@ -150,6 +150,7 @@ information on what to include when reporting a bug.
  - [X11] Bugfix: Content scale fallback value could be inconsistent (#1578)
  - [X11] Bugfix: `glfwMaximizeWindow` had no effect on hidden windows
  - [X11] Bugfix: Clearing `GLFW_FLOATING` on a hidden window caused invalid read
+ - [X11] Bugfix: Changing `GLFW_FLOATING` on a hidden window could silently fail
  - [Wayland] Bugfix: The `GLFW_HAND_CURSOR` shape used the wrong image (#1432)
  - [Wayland] Bugfix: `CLOCK_MONOTONIC` was not correctly enabled
  - [POSIX] Bugfix: `CLOCK_MONOTONIC` was not correctly tested for or enabled

src/x11_window.c

@@ -2628,15 +2628,16 @@ void _glfwPlatformSetWindowFloating(_GLFWwindow* window, GLFWbool enabled)
     }
     else
     {
-        Atom* states;
+        Atom* states = NULL;
         unsigned long i, count;
 
         count = _glfwGetWindowPropertyX11(window->x11.handle,
                                           _glfw.x11.NET_WM_STATE,
                                           XA_ATOM,
                                           (unsigned char**) &states);
-        if (!states)
+
-            return;
+        // NOTE: We don't check for failure as this property may not exist yet
+        //       and that's fine (and we'll create it implicitly with append)
 
         if (enabled)
         {
@@ -2646,31 +2647,35 @@ void _glfwPlatformSetWindowFloating(_GLFWwindow* window, GLFWbool enabled)
                     break;
             }
 
-            if (i == count)
+            if (i < count)
-            {
+                return;
+
             XChangeProperty(_glfw.x11.display, window->x11.handle,
                             _glfw.x11.NET_WM_STATE, XA_ATOM, 32,
                             PropModeAppend,
                             (unsigned char*) &_glfw.x11.NET_WM_STATE_ABOVE,
                             1);
         }
-        }
+        else if (states)
-        else
         {
             for (i = 0;  i < count;  i++)
             {
                 if (states[i] == _glfw.x11.NET_WM_STATE_ABOVE)
-                {
+                    break;
+            }
+
+            if (i == count)
+                return;
+
             states[i] = states[count - 1];
             count--;
-                }
-            }
 
             XChangeProperty(_glfw.x11.display, window->x11.handle,
                             _glfw.x11.NET_WM_STATE, XA_ATOM, 32,
                             PropModeReplace, (unsigned char*) states, count);
         }
 
+        if (states)
             XFree(states);
     }