Wayland: Fix some event types not being processed

If there was already an event available in the Wayland queue, that event
would be processed but other kinds of events (libdecor, key repeat,
joystick connection, etc.) would not be.

This commit restores the processing of all available events on every
call to glfw*Events.  It is partially based on #2842 by jadahl.

Because some libdecor plugins also process non-Wayland events, without
providing an fd for them, libdecor_dispatch is now called
unconditionally.

Fixes #2793
Closes #2795
Related to #2842

README.md

@@ -159,6 +159,8 @@ information on what to include when reporting a bug.
    was suspended (#1350,#2582,#2640,#2719,#2723,#2800,#2827)
  - [Wayland] Bugfix: `glfwPostEmptyEvent` would leak a callback proxy (#2836)
  - [Wayland] Bugfix: `glfwHideWindow` did not always send its request immediately
+ - [Wayland] Bugfix: Some event types were not always processed by `glfwPollEvents` or
+   `glfwWait*Events` (#2793,#2795)
  - [X11] Bugfix: Running without a WM could trigger an assert (#2593,#2601,#2631)
  - [X11] Bugfix: Occasional crash when an idle display awakes (#2766) 
  - [X11] Bugfix: Prevent BadWindow when creating small windows with a content scale

src/wl_window.c

@@ -1375,24 +1375,27 @@ static void handleEvents(double* timeout)
 #endif
 
     GLFWbool event = GLFW_FALSE;
-    enum { DISPLAY_FD, KEYREPEAT_FD, CURSOR_FD, LIBDECOR_FD };
+    enum { DISPLAY_FD, KEYREPEAT_FD, CURSOR_FD };
     struct pollfd fds[] =
     {
         [DISPLAY_FD] = { wl_display_get_fd(_glfw.wl.display), POLLIN },
         [KEYREPEAT_FD] = { _glfw.wl.keyRepeatTimerfd, POLLIN },
-        [CURSOR_FD] = { _glfw.wl.cursorTimerfd, POLLIN },
+        [CURSOR_FD] = { _glfw.wl.cursorTimerfd, POLLIN }
-        [LIBDECOR_FD] = { -1, POLLIN }
     };
 
-    if (_glfw.wl.libdecor.context)
-        fds[LIBDECOR_FD].fd = libdecor_get_fd(_glfw.wl.libdecor.context);
-
     while (!event)
     {
+        if (_glfw.wl.libdecor.context)
+        {
+            // Dispatch unconditionally because it also processes non-Wayland events
+            if (libdecor_dispatch(_glfw.wl.libdecor.context, 0) > 0)
+                event = GLFW_TRUE;
+        }
+
         while (wl_display_prepare_read(_glfw.wl.display) != 0)
         {
             if (wl_display_dispatch_pending(_glfw.wl.display) > 0)
-                return;
+                event = GLFW_TRUE;
         }
 
         // If an error other than EAGAIN happens, we have likely been disconnected
@@ -1411,6 +1414,11 @@ static void handleEvents(double* timeout)
             return;
         }
 
+        double immediate = 0.0;
+
+        if (event)
+            timeout = &immediate;
+
         if (!_glfwPollPOSIX(fds, sizeof(fds) / sizeof(fds[0]), timeout))
         {
             wl_display_cancel_read(_glfw.wl.display);
@@ -1457,12 +1465,6 @@ static void handleEvents(double* timeout)
             if (read(_glfw.wl.cursorTimerfd, &repeats, sizeof(repeats)) == 8)
                 incrementCursorImage();
         }
-
-        if (fds[LIBDECOR_FD].revents & POLLIN)
-        {
-            if (libdecor_dispatch(_glfw.wl.libdecor.context, 0) > 0)
-                event = GLFW_TRUE;
-        }
     }
 }