From 94bb2a138e200308ce8fc908dc74f74c2f071ccf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Camilla=20L=C3=B6wy?= <elmindreda@elmindreda.org>
Date: Mon, 16 Dec 2019 16:09:52 +0100
Subject: [PATCH] X11: Fix updating GLFW_FLOATING on a hidden window

(cherry picked from commit 9db156421f038e5a269a63d59e509f4fb1e2392b)
---
 README.md        |  1 +
 src/x11_window.c | 39 ++++++++++++++++++++++-----------------
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/README.md b/README.md
index 55698e8d..e0b33979 100644
--- a/README.md
+++ b/README.md
@@ -139,6 +139,7 @@ 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)
  - [NSGL] Bugfix: `GLFW_COCOA_RETINA_FRAMEBUFFER` had no effect on newer
    macOS versions (#1442)
diff --git a/src/x11_window.c b/src/x11_window.c
index 8f3844af..6c586c9c 100644
--- a/src/x11_window.c
+++ b/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)
         {
@@ -2646,32 +2647,36 @@ void _glfwPlatformSetWindowFloating(_GLFWwindow* window, GLFWbool enabled)
                     break;
             }
 
-            if (i == count)
-            {
-                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);
-            }
+            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
+        else if (states)
         {
             for (i = 0;  i < count;  i++)
             {
                 if (states[i] == _glfw.x11.NET_WM_STATE_ABOVE)
-                {
-                    states[i] = states[count - 1];
-                    count--;
-                }
+                    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);
         }
 
-        XFree(states);
+        if (states)
+            XFree(states);
     }
 
     XFlush(_glfw.x11.display);