x11: Ignore border extents when the border hint is unset

Old extent events can arrive after the border hint has been unset. Ignore the reported values in this case to avoid reporting bogus border sizes.

src/video/x11/SDL_x11events.c

@@ -884,18 +884,24 @@ void X11_GetBorderValues(SDL_WindowData *data)
     int format;
     unsigned long nitems, bytes_after;
     unsigned char *property;
-    if (X11_XGetWindowProperty(display, data->xwindow, videodata->_NET_FRAME_EXTENTS, 0, 16, 0, XA_CARDINAL, &type, &format, &nitems, &bytes_after, &property) == Success) {
-        if (type != None && nitems == 4) {
-            data->border_left = (int)((long *)property)[0];
-            data->border_right = (int)((long *)property)[1];
-            data->border_top = (int)((long *)property)[2];
-            data->border_bottom = (int)((long *)property)[3];
-        }
-        X11_XFree(property);
+
+    /* Some compositors will send extents even when the border hint is turned off. Ignore them in this case. */
+    if (!(data->window->flags & SDL_WINDOW_BORDERLESS)) {
+        if (X11_XGetWindowProperty(display, data->xwindow, videodata->_NET_FRAME_EXTENTS, 0, 16, 0, XA_CARDINAL, &type, &format, &nitems, &bytes_after, &property) == Success) {
+            if (type != None && nitems == 4) {
+                data->border_left = (int)((long *)property)[0];
+                data->border_right = (int)((long *)property)[1];
+                data->border_top = (int)((long *)property)[2];
+                data->border_bottom = (int)((long *)property)[3];
+            }
+            X11_XFree(property);
 
 #ifdef DEBUG_XEVENTS
-        printf("New _NET_FRAME_EXTENTS: left=%d right=%d, top=%d, bottom=%d\n", data->border_left, data->border_right, data->border_top, data->border_bottom);
+            printf("New _NET_FRAME_EXTENTS: left=%d right=%d, top=%d, bottom=%d\n", data->border_left, data->border_right, data->border_top, data->border_bottom);
 #endif
+        }
+    } else {
+        data->border_left = data->border_top = data->border_right = data->border_bottom = 0;
     }
 }
 
@@ -1745,11 +1751,10 @@ static void X11_DispatchEvent(SDL_VideoDevice *_this, XEvent *xevent)
                     X11_XMoveWindow(display, data->xwindow, data->window->floating.x - data->border_left, data->window->floating.y - data->border_top);
                     X11_XResizeWindow(display, data->xwindow, data->window->floating.w, data->window->floating.h);
                 }
-
-                if (!(data->window->flags & SDL_WINDOW_FULLSCREEN) && data->toggle_borders) {
-                    data->toggle_borders = SDL_FALSE;
-                    X11_SetWindowBordered(_this, data->window, !(data->window->flags & SDL_WINDOW_BORDERLESS));
-                }
+            }
+            if (!(data->window->flags & SDL_WINDOW_FULLSCREEN) && data->toggle_borders) {
+                data->toggle_borders = SDL_FALSE;
+                X11_SetWindowBordered(_this, data->window, !(data->window->flags & SDL_WINDOW_BORDERLESS));
             }
         }
     } break;

src/video/x11/SDL_x11window.c

@@ -1233,11 +1233,7 @@ void X11_SetWindowBordered(SDL_VideoDevice *_this, SDL_Window *window, SDL_bool
         X11_XCheckIfEvent(display, &event, &isMapNotify, (XPointer)&data->xwindow);
 
         /* Turning the borders off doesn't send an extent event, so they must be cleared here. */
-        if (bordered) {
-            X11_GetBorderValues(data);
-        } else {
-            data->border_top = data->border_left = data->border_bottom = data->border_right = 0;
-        }
+        X11_GetBorderValues(data);
 
         /* Make sure the window manager didn't resize our window for the difference. */
         X11_XResizeWindow(display, data->xwindow, window->floating.w, window->floating.h);