From 85a2a201b1511970c8def54c51d94f76184282a4 Mon Sep 17 00:00:00 2001
From: Frank Praznik <frank.praznik@gmail.com>
Date: Fri, 31 May 2024 19:06:09 -0400
Subject: [PATCH] x11: Always disable the borders when leaving fullscreen from
 a borderless window created as fullscreen

Borderless windows flagged as fullscreen at creation time turn on the borders, because doing so prevents some window managers from wrongly positioning the borderless window, and in these cases the borders need to be removed whether fullscreen is exited programmatically or via a compositor event. Set a flag when forcing the borders on, so they will be removed in all cases later.
---
 src/video/x11/SDL_x11events.c | 6 ++++++
 src/video/x11/SDL_x11window.c | 9 +++++----
 src/video/x11/SDL_x11window.h | 1 +
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/video/x11/SDL_x11events.c b/src/video/x11/SDL_x11events.c
index 2201c46414..64e06a644f 100644
--- a/src/video/x11/SDL_x11events.c
+++ b/src/video/x11/SDL_x11events.c
@@ -1723,6 +1723,12 @@ static void X11_DispatchEvent(SDL_VideoDevice *_this, XEvent *xevent)
 
                         /* Need to restore or update any limits changed while the window was fullscreen. */
                         X11_SetWindowMinMax(data->window, !!(flags & SDL_WINDOW_MAXIMIZED));
+
+                        /* Toggle the borders if they were forced on while creating a borderless fullscreen window. */
+                        if (data->fullscreen_borders_forced_on) {
+                            data->toggle_borders = SDL_TRUE;
+                            data->fullscreen_borders_forced_on = SDL_FALSE;
+                        }
                     }
 
                     if ((flags & SDL_WINDOW_FULLSCREEN) &&
diff --git a/src/video/x11/SDL_x11window.c b/src/video/x11/SDL_x11window.c
index fda1f07812..628e21206f 100644
--- a/src/video/x11/SDL_x11window.c
+++ b/src/video/x11/SDL_x11window.c
@@ -755,6 +755,10 @@ int X11_CreateWindow(SDL_VideoDevice *_this, SDL_Window *window, SDL_PropertiesI
     }
     windowdata = window->driverdata;
 
+    /* Set the flag if the borders were forced on when creating a fullscreen window for later removal. */
+    windowdata->fullscreen_borders_forced_on = !!(window->pending_flags & SDL_WINDOW_FULLSCREEN) &&
+                                               !!(window->flags & SDL_WINDOW_BORDERLESS);
+
 #if defined(SDL_VIDEO_OPENGL_ES) || defined(SDL_VIDEO_OPENGL_ES2) || defined(SDL_VIDEO_OPENGL_EGL)
     if ((window->flags & SDL_WINDOW_OPENGL) &&
         ((_this->gl_config.profile_mask == SDL_GL_CONTEXT_PROFILE_ES) ||
@@ -1320,6 +1324,7 @@ void X11_SetWindowBordered(SDL_VideoDevice *_this, SDL_Window *window, SDL_bool
     } else {
         /* If fullscreen, set a flag to toggle the borders when returning to windowed mode. */
         data->toggle_borders = SDL_TRUE;
+        data->fullscreen_borders_forced_on = SDL_FALSE;
     }
 }
 
@@ -1734,10 +1739,6 @@ static int X11_SetWindowFullscreenViaWM(SDL_VideoDevice *_this, SDL_Window *wind
         X11_SetNetWMState(_this, data->xwindow, flags);
     }
 
-    if ((window->flags & SDL_WINDOW_BORDERLESS) && !fullscreen) {
-        SetWindowBordered(display, displaydata->screen, data->xwindow, SDL_FALSE);
-    }
-
     if (data->visual->class == DirectColor) {
         if (fullscreen) {
             X11_XInstallColormap(display, data->colormap);
diff --git a/src/video/x11/SDL_x11window.h b/src/video/x11/SDL_x11window.h
index 204c7e4af5..0681bf7dfb 100644
--- a/src/video/x11/SDL_x11window.h
+++ b/src/video/x11/SDL_x11window.h
@@ -101,6 +101,7 @@ struct SDL_WindowData
     SDL_bool disable_size_position_events;
     SDL_bool previous_borders_nonzero;
     SDL_bool toggle_borders;
+    SDL_bool fullscreen_borders_forced_on;
     SDL_HitTestResult hit_test_result;
 };