Fixed missing ICCCM protocol message checks.

README.md

@@ -67,6 +67,7 @@ The following dependencies are needed by the examples and test programs:
                  cause an uncaught `BadWindow` error
  - [X11] Bugfix: No check was made for the presence GLX 1.3 when
                  `GLX_SGIX_fbconfig` was unavailable
+ - [X11] Bugfix: The message type of ICCCM protocol events was not checked
 
 
 ## Contact

src/x11_init.c

@@ -430,6 +430,9 @@ static GLboolean initExtensions(void)
     Bool supported;
 
     // Find or create window manager atoms
+    _glfw.x11.WM_PROTOCOLS = XInternAtom(_glfw.x11.display,
+                                         "WM_PROTOCOLS",
+                                         False);
     _glfw.x11.WM_STATE = XInternAtom(_glfw.x11.display, "WM_STATE", False);
     _glfw.x11.WM_DELETE_WINDOW = XInternAtom(_glfw.x11.display,
                                              "WM_DELETE_WINDOW",

src/x11_platform.h

@@ -107,6 +107,7 @@ typedef struct _GLFWlibraryX11
     XContext        context;
 
     // Window manager atoms
+    Atom            WM_PROTOCOLS;
     Atom            WM_STATE;
     Atom            WM_DELETE_WINDOW;
     Atom            NET_WM_NAME;

src/x11_window.c

@@ -739,7 +739,13 @@ static void processEvent(XEvent *event)
         {
             // Custom client message, probably from the window manager
 
-            if ((Atom) event->xclient.data.l[0] == _glfw.x11.WM_DELETE_WINDOW)
+            if (event->xclient.message_type == None)
+                break;
+
+            if (event->xclient.message_type == _glfw.x11.WM_PROTOCOLS)
+            {
+                if (_glfw.x11.WM_DELETE_WINDOW &&
+                    (Atom) event->xclient.data.l[0] == _glfw.x11.WM_DELETE_WINDOW)
                 {
                     // The window manager was asked to close the window, for example by
                     // the user pressing a 'close' window decoration button
@@ -759,6 +765,7 @@ static void processEvent(XEvent *event)
                             SubstructureNotifyMask | SubstructureRedirectMask,
                             event);
                 }
+            }
             else if (event->xclient.message_type == _glfw.x11.XdndEnter)
             {
                 // A drag operation has entered the window