Merge c371f4cb7d into 161fb1b6f6

The fallback decorations would emit scroll events as if scrolling had
occurred over the content area of the window.

README.md

@@ -134,6 +134,10 @@ information on what to include when reporting a bug.
  - [Wayland] Bugfix: Ignore key repeat events when no window has keyboard focus (#2727)
  - [Wayland] Bugfix: Reset key repeat timer when window destroyed (#2741,#2727)
  - [Wayland] Bugfix: Memory would leak if reading a data offer failed midway
+ - [Wayland] Bugfix: Keyboard leave event handler now processes key repeats (#2736)
+ - [Wayland] Bugfix: Retrieved cursor position would be incorrect when hovering over
+                     fallback decorations
+ - [Wayland] Bugfix: Fallback decorations would report scroll events
  - [X11] Bugfix: Running without a WM could trigger an assert (#2593,#2601,#2631)
  - [Null] Added Vulkan 'window' surface creation via `VK_EXT_headless_surface`
  - [Null] Added EGL context creation on Mesa via `EGL_MESA_platform_surfaceless`

include/GLFW/glfw3.h

@@ -1102,6 +1102,7 @@ extern "C" {
  *  [window hint](@ref GLFW_SCALE_FRAMEBUFFER_hint).
  */
 #define GLFW_SCALE_FRAMEBUFFER      0x0002200D
+#define GLFW_FULLSCREEN             0x0002200E
 /*! @brief Legacy name for compatibility.
  *
  *  This is an alias for the

src/cocoa_init.m

@@ -555,6 +555,7 @@ GLFWbool _glfwConnectCocoa(int platformID, _GLFWplatform* platform)
         .setWindowFloating = _glfwSetWindowFloatingCocoa,
         .setWindowOpacity = _glfwSetWindowOpacityCocoa,
         .setWindowMousePassthrough = _glfwSetWindowMousePassthroughCocoa,
+        .getWindowIsFullscreen = _glfwGetWindowIsFullscreenNull,
         .pollEvents = _glfwPollEventsCocoa,
         .waitEvents = _glfwWaitEventsCocoa,
         .waitEventsTimeout = _glfwWaitEventsTimeoutCocoa,

src/cocoa_platform.h

@@ -247,6 +247,7 @@ void _glfwSetWindowFloatingCocoa(_GLFWwindow* window, GLFWbool enabled);
 float _glfwGetWindowOpacityCocoa(_GLFWwindow* window);
 void _glfwSetWindowOpacityCocoa(_GLFWwindow* window, float opacity);
 void _glfwSetWindowMousePassthroughCocoa(_GLFWwindow* window, GLFWbool enabled);
+GLFWbool _glfwGetWindowIsFullscreenCocoa(_GLFWwindow* window);
 
 void _glfwSetRawMouseMotionCocoa(_GLFWwindow *window, GLFWbool enabled);
 GLFWbool _glfwRawMouseMotionSupportedCocoa(void);

src/internal.h

@@ -747,6 +747,7 @@ struct _GLFWplatform
     void (*setWindowFloating)(_GLFWwindow*,GLFWbool);
     void (*setWindowOpacity)(_GLFWwindow*,float);
     void (*setWindowMousePassthrough)(_GLFWwindow*,GLFWbool);
+    GLFWbool (*getWindowIsFullscreen) (_GLFWwindow*);
     void (*pollEvents)(void);
     void (*waitEvents)(void);
     void (*waitEventsTimeout)(double);

src/null_platform.h

@@ -243,6 +243,8 @@ void _glfwSetWindowResizableNull(_GLFWwindow* window, GLFWbool enabled);
 void _glfwSetWindowDecoratedNull(_GLFWwindow* window, GLFWbool enabled);
 void _glfwSetWindowFloatingNull(_GLFWwindow* window, GLFWbool enabled);
 void _glfwSetWindowMousePassthroughNull(_GLFWwindow* window, GLFWbool enabled);
+GLFWbool _glfwGetWindowIsFullscreenNull(_GLFWwindow* window);
+
 float _glfwGetWindowOpacityNull(_GLFWwindow* window);
 void _glfwSetWindowOpacityNull(_GLFWwindow* window, float opacity);
 void _glfwSetRawMouseMotionNull(_GLFWwindow *window, GLFWbool enabled);

src/null_window.c

@@ -408,6 +408,11 @@ void _glfwSetWindowMousePassthroughNull(_GLFWwindow* window, GLFWbool enabled)
 {
 }
 
+GLFWbool _glfwGetWindowIsFullscreenNull(_GLFWwindow* window)
+{
+    return 0;
+}
+
 float _glfwGetWindowOpacityNull(_GLFWwindow* window)
 {
     return window->null.opacity;

src/win32_init.c

@@ -660,6 +660,7 @@ GLFWbool _glfwConnectWin32(int platformID, _GLFWplatform* platform)
         .setWindowFloating = _glfwSetWindowFloatingWin32,
         .setWindowOpacity = _glfwSetWindowOpacityWin32,
         .setWindowMousePassthrough = _glfwSetWindowMousePassthroughWin32,
+        .getWindowIsFullscreen = _glfwGetWindowIsFullscreenNull,
         .pollEvents = _glfwPollEventsWin32,
         .waitEvents = _glfwWaitEventsWin32,
         .waitEventsTimeout = _glfwWaitEventsTimeoutWin32,

src/win32_platform.h

@@ -513,6 +513,7 @@ void _glfwSetWindowResizableWin32(_GLFWwindow* window, GLFWbool enabled);
 void _glfwSetWindowDecoratedWin32(_GLFWwindow* window, GLFWbool enabled);
 void _glfwSetWindowFloatingWin32(_GLFWwindow* window, GLFWbool enabled);
 void _glfwSetWindowMousePassthroughWin32(_GLFWwindow* window, GLFWbool enabled);
+GLFWbool _glfwGetWindowIsFullscreenWin32(_GLFWwindow* window);
 float _glfwGetWindowOpacityWin32(_GLFWwindow* window);
 void _glfwSetWindowOpacityWin32(_GLFWwindow* window, float opacity);
 

src/window.c

@@ -900,6 +900,8 @@ GLFWAPI int glfwGetWindowAttrib(GLFWwindow* handle, int attrib)
             return window->focusOnShow;
         case GLFW_MOUSE_PASSTHROUGH:
             return window->mousePassthrough;
+        case GLFW_FULLSCREEN:
+            return _glfw.platform.getWindowIsFullscreen(window);
         case GLFW_TRANSPARENT_FRAMEBUFFER:
             return _glfw.platform.framebufferTransparent(window);
         case GLFW_RESIZABLE:

src/wl_init.c

@@ -506,6 +506,7 @@ GLFWbool _glfwConnectWayland(int platformID, _GLFWplatform* platform)
         .setWindowFloating = _glfwSetWindowFloatingWayland,
         .setWindowOpacity = _glfwSetWindowOpacityWayland,
         .setWindowMousePassthrough = _glfwSetWindowMousePassthroughWayland,
+        .getWindowIsFullscreen = _glfwGetWindowIsFullscreenNull,
         .pollEvents = _glfwPollEventsWayland,
         .waitEvents = _glfwWaitEventsWayland,
         .waitEventsTimeout = _glfwWaitEventsTimeoutWayland,

src/wl_platform.h

@@ -413,6 +413,8 @@ typedef struct _GLFWwindowWayland
         struct wl_buffer*           buffer;
         _GLFWfallbackEdgeWayland    top, left, right, bottom;
         struct wl_surface*          focus;
+        wl_fixed_t                  pointerX, pointerY;
+        const char*                 cursorName;
     } fallback;
 } _GLFWwindowWayland;
 
@@ -454,7 +456,6 @@ typedef struct _GLFWlibraryWayland
     struct wl_cursor_theme*     cursorTheme;
     struct wl_cursor_theme*     cursorThemeHiDPI;
     struct wl_surface*          cursorSurface;
-    const char*                 cursorPreviousName;
     int                         cursorTimerfd;
     uint32_t                    serial;
     uint32_t                    pointerEnterSerial;
@@ -648,6 +649,7 @@ void _glfwSetWindowFloatingWayland(_GLFWwindow* window, GLFWbool enabled);
 float _glfwGetWindowOpacityWayland(_GLFWwindow* window);
 void _glfwSetWindowOpacityWayland(_GLFWwindow* window, float opacity);
 void _glfwSetWindowMousePassthroughWayland(_GLFWwindow* window, GLFWbool enabled);
+GLFWbool _glfwGetWindowIsFullscreenWayland(_GLFWwindow* window);
 
 void _glfwSetRawMouseMotionWayland(_GLFWwindow* window, GLFWbool enabled);
 GLFWbool _glfwRawMouseMotionSupportedWayland(void);

src/wl_window.c

@@ -275,6 +275,146 @@ static void destroyFallbackDecorations(_GLFWwindow* window)
     destroyFallbackEdge(&window->wl.fallback.bottom);
 }
 
+static void updateFallbackDecorationCursor(_GLFWwindow* window,
+                                           wl_fixed_t sx,
+                                           wl_fixed_t sy)
+{
+    window->wl.fallback.pointerX = sx;
+    window->wl.fallback.pointerY = sy;
+
+    const double xpos = wl_fixed_to_double(sx);
+    const double ypos = wl_fixed_to_double(sy);
+    const char* cursorName = "left_ptr";
+
+    if (window->resizable)
+    {
+        if (window->wl.fallback.focus == window->wl.fallback.top.surface)
+        {
+            if (ypos < GLFW_BORDER_SIZE)
+                cursorName = "n-resize";
+        }
+        else if (window->wl.fallback.focus == window->wl.fallback.left.surface)
+        {
+            if (ypos < GLFW_BORDER_SIZE)
+                cursorName = "nw-resize";
+            else
+                cursorName = "w-resize";
+        }
+        else if (window->wl.fallback.focus == window->wl.fallback.right.surface)
+        {
+            if (ypos < GLFW_BORDER_SIZE)
+                cursorName = "ne-resize";
+            else
+                cursorName = "e-resize";
+        }
+        else if (window->wl.fallback.focus == window->wl.fallback.bottom.surface)
+        {
+            if (xpos < GLFW_BORDER_SIZE)
+                cursorName = "sw-resize";
+            else if (xpos > window->wl.width + GLFW_BORDER_SIZE)
+                cursorName = "se-resize";
+            else
+                cursorName = "s-resize";
+        }
+    }
+
+    if (window->wl.fallback.cursorName != cursorName)
+    {
+        struct wl_surface* surface = _glfw.wl.cursorSurface;
+        struct wl_cursor_theme* theme = _glfw.wl.cursorTheme;
+        int scale = 1;
+
+        if (window->wl.bufferScale > 1 && _glfw.wl.cursorThemeHiDPI)
+        {
+            // We only support up to scale=2 for now, since libwayland-cursor
+            // requires us to load a different theme for each size.
+            scale = 2;
+            theme = _glfw.wl.cursorThemeHiDPI;
+        }
+
+        struct wl_cursor* cursor = wl_cursor_theme_get_cursor(theme, cursorName);
+        if (!cursor)
+            return;
+
+        // TODO: handle animated cursors too.
+        struct wl_cursor_image* image = cursor->images[0];
+        if (!image)
+            return;
+
+        struct wl_buffer* buffer = wl_cursor_image_get_buffer(image);
+        if (!buffer)
+            return;
+
+        wl_pointer_set_cursor(_glfw.wl.pointer, _glfw.wl.pointerEnterSerial,
+                              surface,
+                              image->hotspot_x / scale,
+                              image->hotspot_y / scale);
+        wl_surface_set_buffer_scale(surface, scale);
+        wl_surface_attach(surface, buffer, 0, 0);
+        wl_surface_damage(surface, 0, 0, image->width, image->height);
+        wl_surface_commit(surface);
+
+        window->wl.fallback.cursorName = cursorName;
+    }
+}
+
+static void handleFallbackDecorationButton(_GLFWwindow* window,
+                                           uint32_t serial,
+                                           uint32_t button)
+{
+    const double xpos = wl_fixed_to_double(window->wl.fallback.pointerX);
+    const double ypos = wl_fixed_to_double(window->wl.fallback.pointerY);
+
+    if (button == BTN_LEFT)
+    {
+        uint32_t edges = XDG_TOPLEVEL_RESIZE_EDGE_NONE;
+
+        if (window->wl.fallback.focus == window->wl.fallback.top.surface)
+        {
+            if (ypos < GLFW_BORDER_SIZE)
+                edges = XDG_TOPLEVEL_RESIZE_EDGE_TOP;
+            else
+                xdg_toplevel_move(window->wl.xdg.toplevel, _glfw.wl.seat, serial);
+        }
+        else if (window->wl.fallback.focus == window->wl.fallback.left.surface)
+        {
+            if (ypos < GLFW_BORDER_SIZE)
+                edges = XDG_TOPLEVEL_RESIZE_EDGE_TOP_LEFT;
+            else
+                edges = XDG_TOPLEVEL_RESIZE_EDGE_LEFT;
+        }
+        else if (window->wl.fallback.focus == window->wl.fallback.right.surface)
+        {
+            if (ypos < GLFW_BORDER_SIZE)
+                edges = XDG_TOPLEVEL_RESIZE_EDGE_TOP_RIGHT;
+            else
+                edges = XDG_TOPLEVEL_RESIZE_EDGE_RIGHT;
+        }
+        else if (window->wl.fallback.focus == window->wl.fallback.bottom.surface)
+        {
+            if (xpos < GLFW_BORDER_SIZE)
+                edges = XDG_TOPLEVEL_RESIZE_EDGE_BOTTOM_LEFT;
+            else if (xpos > window->wl.width + GLFW_BORDER_SIZE)
+                edges = XDG_TOPLEVEL_RESIZE_EDGE_BOTTOM_RIGHT;
+            else
+                edges = XDG_TOPLEVEL_RESIZE_EDGE_BOTTOM;
+        }
+
+        if (edges != XDG_TOPLEVEL_RESIZE_EDGE_NONE)
+            xdg_toplevel_resize(window->wl.xdg.toplevel, _glfw.wl.seat, serial, edges);
+    }
+    else if (button == BTN_RIGHT)
+    {
+        if (window->wl.xdg.toplevel)
+        {
+            xdg_toplevel_show_window_menu(window->wl.xdg.toplevel,
+                                          _glfw.wl.seat, serial,
+                                          window->wl.cursorPosX,
+                                          window->wl.cursorPosY);
+        }
+    }
+}
+
 static void xdgDecorationHandleConfigure(void* userData,
                                          struct zxdg_toplevel_decoration_v1* decoration,
                                          uint32_t mode)
@@ -1417,7 +1557,6 @@ static void pointerHandleLeave(void* userData,
 
     _glfw.wl.serial = serial;
     _glfw.wl.pointerFocus = NULL;
-    _glfw.wl.cursorPreviousName = NULL;
 
     if (window->wl.hovered)
     {
@@ -1427,7 +1566,10 @@ static void pointerHandleLeave(void* userData,
     else
     {
         if (window->wl.fallback.decorations)
+        {
             window->wl.fallback.focus = NULL;
+            window->wl.fallback.cursorName = NULL;
+        }
     }
 }
 
@@ -1444,92 +1586,16 @@ static void pointerHandleMotion(void* userData,
     if (window->cursorMode == GLFW_CURSOR_DISABLED)
         return;
 
-    const double xpos = wl_fixed_to_double(sx);
-    const double ypos = wl_fixed_to_double(sy);
-    window->wl.cursorPosX = xpos;
-    window->wl.cursorPosY = ypos;
-
     if (window->wl.hovered)
     {
-        _glfw.wl.cursorPreviousName = NULL;
-        _glfwInputCursorPos(window, xpos, ypos);
-        return;
+        window->wl.cursorPosX = wl_fixed_to_double(sx);
+        window->wl.cursorPosY = wl_fixed_to_double(sy);
+        _glfwInputCursorPos(window, window->wl.cursorPosX, window->wl.cursorPosY);
     }
-
+    else
+    {
         if (window->wl.fallback.decorations)
-    {
-        const char* cursorName = "left_ptr";
-
-        if (window->resizable)
-        {
-            if (window->wl.fallback.focus == window->wl.fallback.top.surface)
-            {
-                if (ypos < GLFW_BORDER_SIZE)
-                    cursorName = "n-resize";
-            }
-            else if (window->wl.fallback.focus == window->wl.fallback.left.surface)
-            {
-                if (ypos < GLFW_BORDER_SIZE)
-                    cursorName = "nw-resize";
-                else
-                    cursorName = "w-resize";
-            }
-            else if (window->wl.fallback.focus == window->wl.fallback.right.surface)
-            {
-                if (ypos < GLFW_BORDER_SIZE)
-                    cursorName = "ne-resize";
-                else
-                    cursorName = "e-resize";
-            }
-            else if (window->wl.fallback.focus == window->wl.fallback.bottom.surface)
-            {
-                if (xpos < GLFW_BORDER_SIZE)
-                    cursorName = "sw-resize";
-                else if (xpos > window->wl.width + GLFW_BORDER_SIZE)
-                    cursorName = "se-resize";
-                else
-                    cursorName = "s-resize";
-            }
-        }
-
-        if (_glfw.wl.cursorPreviousName != cursorName)
-        {
-            struct wl_surface* surface = _glfw.wl.cursorSurface;
-            struct wl_cursor_theme* theme = _glfw.wl.cursorTheme;
-            int scale = 1;
-
-            if (window->wl.bufferScale > 1 && _glfw.wl.cursorThemeHiDPI)
-            {
-                // We only support up to scale=2 for now, since libwayland-cursor
-                // requires us to load a different theme for each size.
-                scale = 2;
-                theme = _glfw.wl.cursorThemeHiDPI;
-            }
-
-            struct wl_cursor* cursor = wl_cursor_theme_get_cursor(theme, cursorName);
-            if (!cursor)
-                return;
-
-            // TODO: handle animated cursors too.
-            struct wl_cursor_image* image = cursor->images[0];
-            if (!image)
-                return;
-
-            struct wl_buffer* buffer = wl_cursor_image_get_buffer(image);
-            if (!buffer)
-                return;
-
-            wl_pointer_set_cursor(_glfw.wl.pointer, _glfw.wl.pointerEnterSerial,
-                                  surface,
-                                  image->hotspot_x / scale,
-                                  image->hotspot_y / scale);
-            wl_surface_set_buffer_scale(surface, scale);
-            wl_surface_attach(surface, buffer, 0, 0);
-            wl_surface_damage(surface, 0, 0, image->width, image->height);
-            wl_surface_commit(surface);
-
-            _glfw.wl.cursorPreviousName = cursorName;
-        }
+            updateFallbackDecorationCursor(window, sx, sy);
     }
 }
 
@@ -1552,62 +1618,11 @@ static void pointerHandleButton(void* userData,
                              button - BTN_LEFT,
                              state == WL_POINTER_BUTTON_STATE_PRESSED,
                              _glfw.wl.xkb.modifiers);
-        return;
     }
-
+    else
+    {
         if (window->wl.fallback.decorations)
-    {
-        if (button == BTN_LEFT)
-        {
-            uint32_t edges = XDG_TOPLEVEL_RESIZE_EDGE_NONE;
-
-            if (window->wl.fallback.focus == window->wl.fallback.top.surface)
-            {
-                if (window->wl.cursorPosY < GLFW_BORDER_SIZE)
-                    edges = XDG_TOPLEVEL_RESIZE_EDGE_TOP;
-                else
-                    xdg_toplevel_move(window->wl.xdg.toplevel, _glfw.wl.seat, serial);
-            }
-            else if (window->wl.fallback.focus == window->wl.fallback.left.surface)
-            {
-                if (window->wl.cursorPosY < GLFW_BORDER_SIZE)
-                    edges = XDG_TOPLEVEL_RESIZE_EDGE_TOP_LEFT;
-                else
-                    edges = XDG_TOPLEVEL_RESIZE_EDGE_LEFT;
-            }
-            else if (window->wl.fallback.focus == window->wl.fallback.right.surface)
-            {
-                if (window->wl.cursorPosY < GLFW_BORDER_SIZE)
-                    edges = XDG_TOPLEVEL_RESIZE_EDGE_TOP_RIGHT;
-                else
-                    edges = XDG_TOPLEVEL_RESIZE_EDGE_RIGHT;
-            }
-            else if (window->wl.fallback.focus == window->wl.fallback.bottom.surface)
-            {
-                if (window->wl.cursorPosX < GLFW_BORDER_SIZE)
-                    edges = XDG_TOPLEVEL_RESIZE_EDGE_BOTTOM_LEFT;
-                else if (window->wl.cursorPosX > window->wl.width + GLFW_BORDER_SIZE)
-                    edges = XDG_TOPLEVEL_RESIZE_EDGE_BOTTOM_RIGHT;
-                else
-                    edges = XDG_TOPLEVEL_RESIZE_EDGE_BOTTOM;
-            }
-
-            if (edges != XDG_TOPLEVEL_RESIZE_EDGE_NONE)
-            {
-                xdg_toplevel_resize(window->wl.xdg.toplevel, _glfw.wl.seat,
-                                    serial, edges);
-            }
-        }
-        else if (button == BTN_RIGHT)
-        {
-            if (window->wl.xdg.toplevel)
-            {
-                xdg_toplevel_show_window_menu(window->wl.xdg.toplevel,
-                                              _glfw.wl.seat, serial,
-                                              window->wl.cursorPosX,
-                                              window->wl.cursorPosY);
-            }
-        }
+            handleFallbackDecorationButton(window, serial, button);
     }
 }
 
@@ -1621,12 +1636,15 @@ static void pointerHandleAxis(void* userData,
     if (!window)
         return;
 
+    if (window->wl.hovered)
+    {
         // NOTE: 10 units of motion per mouse wheel step seems to be a common ratio
         if (axis == WL_POINTER_AXIS_HORIZONTAL_SCROLL)
             _glfwInputScroll(window, -wl_fixed_to_double(value) / 10.0, 0.0);
         else if (axis == WL_POINTER_AXIS_VERTICAL_SCROLL)
             _glfwInputScroll(window, 0.0, -wl_fixed_to_double(value) / 10.0);
     }
+}
 
 static const struct wl_pointer_listener pointerListener =
 {
@@ -1760,6 +1778,24 @@ static void keyboardHandleLeave(void* userData,
     if (!window)
         return;
 
+    // Handle any key repeats up to this point. We don't poll as this should be infrequent.
+    uint64_t repeats;
+    if (read(_glfw.wl.keyRepeatTimerfd, &repeats, sizeof(repeats)) == 8)
+    {
+        if(_glfw.wl.keyboardFocus)
+        {
+            for (uint64_t i = 0; i < repeats; i++)
+            {
+                _glfwInputKey(_glfw.wl.keyboardFocus,
+                              translateKey(_glfw.wl.keyRepeatScancode),
+                              _glfw.wl.keyRepeatScancode,
+                              GLFW_PRESS,
+                              _glfw.wl.xkb.modifiers);
+                inputText(_glfw.wl.keyboardFocus, _glfw.wl.keyRepeatScancode);
+            }
+        }
+    }
+
     struct itimerspec timer = {0};
     timerfd_settime(_glfw.wl.keyRepeatTimerfd, 0, &timer, NULL);
 

src/x11_init.c

@@ -1237,6 +1237,7 @@ GLFWbool _glfwConnectX11(int platformID, _GLFWplatform* platform)
         .setWindowFloating = _glfwSetWindowFloatingX11,
         .setWindowOpacity = _glfwSetWindowOpacityX11,
         .setWindowMousePassthrough = _glfwSetWindowMousePassthroughX11,
+        .getWindowIsFullscreen = _glfwGetWindowIsFullscreenX11,
         .pollEvents = _glfwPollEventsX11,
         .waitEvents = _glfwWaitEventsX11,
         .waitEventsTimeout = _glfwWaitEventsTimeoutX11,

src/x11_platform.h

@@ -934,6 +934,7 @@ void _glfwSetWindowFloatingX11(_GLFWwindow* window, GLFWbool enabled);
 float _glfwGetWindowOpacityX11(_GLFWwindow* window);
 void _glfwSetWindowOpacityX11(_GLFWwindow* window, float opacity);
 void _glfwSetWindowMousePassthroughX11(_GLFWwindow* window, GLFWbool enabled);
+GLFWbool _glfwGetWindowIsFullscreenX11(_GLFWwindow* window);
 
 void _glfwSetRawMouseMotionX11(_GLFWwindow *window, GLFWbool enabled);
 GLFWbool _glfwRawMouseMotionSupportedX11(void);

src/x11_window.c

@@ -2729,6 +2729,51 @@ void _glfwSetWindowMousePassthroughX11(_GLFWwindow* window, GLFWbool enabled)
     }
 }
 
+GLFWbool _glfwGetWindowIsFullscreenX11(_GLFWwindow* window)
+{
+    Atom wm_state = XInternAtom(_glfw.x11.display, "_NET_WM_STATE", True);
+    Atom wm_state_fullscreen = XInternAtom(_glfw.x11.display, "_NET_WM_STATE_FULLSCREEN", True);
+
+    Atom type = XA_ATOM;
+    int format;
+    size_t nItems;
+    size_t bytesAfterReturn;
+    Atom* prop;
+    
+    int result = XGetWindowProperty(
+        _glfw.x11.display,
+        window->x11.handle,
+        wm_state, 
+        0,
+        ~0L,
+        False,
+        AnyPropertyType,
+        &type,
+        &format,
+        &nItems,
+        &bytesAfterReturn,
+        (unsigned char**)&prop 
+    );
+
+    assert(result == Success);
+    assert(nItems > 0);
+
+    if (!prop) {
+        return 0;
+    }
+
+    GLFWbool isFullscreen = 0;
+    for (int i = 0; i < nItems; i++) {
+        if (prop[i] == wm_state_fullscreen) {
+            isFullscreen = 1;
+        }
+    }
+
+    XFree(prop);
+    
+    return isFullscreen;
+}
+
 float _glfwGetWindowOpacityX11(_GLFWwindow* window)
 {
     float opacity = 1.f;

tests/window.c

@@ -441,6 +441,7 @@ int main(int argc, char** argv)
             nk_value_bool(nk, "Visible", glfwGetWindowAttrib(window, GLFW_VISIBLE));
             nk_value_bool(nk, "Iconified", glfwGetWindowAttrib(window, GLFW_ICONIFIED));
             nk_value_bool(nk, "Maximized", glfwGetWindowAttrib(window, GLFW_MAXIMIZED));
+            nk_value_bool(nk, "Fullscreen", glfwGetWindowAttrib(window, GLFW_FULLSCREEN));
         }
         nk_end(nk);