Flatpak: drop the WebKit NVIDIA export; the binary owns the workaround

/proc/driver/nvidia/version is readable inside the Flatpak sandbox, so the
binary's NVIDIA branch already sets WEBKIT_DMABUF_RENDERER_FORCE_SHM with
the correct runtime gate and the entrypoint's own export is redundant.

Verified with:
  flatpak run --command=cat com.orcaslicer.OrcaSlicer /proc/driver/nvidia/version
which prints the NVRM version (driver 615.71.09) from inside the sandbox.

.claude/skills/orca-wxwidgets/references/platforms.md

@@ -569,12 +569,16 @@ on the **first** call. So:
 #endif
 ```
 
-**Before GTK starts**, only the environment exists. `CLI::run` (`src/OrcaSlicer.cpp`) branches on
+**Before GTK starts**, only the environment exists. `CLI::run` (`src/OrcaSlicer.cpp`) sets the NVIDIA
-`GDK_BACKEND` (an `x11` prefix means the X11 opt-in). On the default path it forces `GDK_BACKEND=x11`
+DMABUF workaround and then branches on `GDK_BACKEND` (an `x11` prefix means the X11 opt-in). On both
-when wx lacks EGL and `WAYLAND_DISPLAY` is set. It sets `WEBKIT_DISABLE_COMPOSITING_MODE=1`
+paths, when `/proc/driver/nvidia/version` exists and the linked WebKitGTK honours the switch (>= 2.44,
-(non-replacing) only when both `DISPLAY` and `WAYLAND_DISPLAY` are set, and calls `XInitThreads()`
+`WebView::SupportsForceSharedMemory()`), it sets `WEBKIT_DMABUF_RENDERER_FORCE_SHM=1` and
+`WEBKIT_FORCE_DMABUF_RENDERER=1` (non-replacing): the proprietary driver cannot back WebKit's hardware
+DMABUF renderer. On the default path it forces `GDK_BACKEND=x11` when wx lacks EGL and `WAYLAND_DISPLAY`
+is set. It sets `WEBKIT_DISABLE_COMPOSITING_MODE=1` (non-replacing) only when both `DISPLAY` and
+`WAYLAND_DISPLAY` are set and the linked WebKitGTK is older than 2.42, and calls `XInitThreads()`
 only when `DISPLAY` is set. With neither variable set, the GUI refuses to start ("Neither DISPLAY nor
-WAYLAND_DISPLAY set"). The details and the WebKit rule (c12912e0df) are in
+WAYLAND_DISPLAY set"). The details and the WebKit rules (c12912e0df) are in
 `references/webview-gl-aui-media.md` §WebKitGTK on Linux sessions.
 
 **wx's own detectors**, for reference:

.claude/skills/orca-wxwidgets/references/webview-gl-aui-media.md

@@ -61,7 +61,8 @@ available; GTK2/WebKit1 is an opt-out configuration the GUI does not support.
 11. A web host that re-themes in place handles `EVT_WEBVIEW_RECREATED` without `Skip()`; one that
     needs a reload lets it through. §[Orca wrapper](#orca-webview-wrapper-widgetswebview)
 12. Keep `WebViewWebKit`'s destructor removing the `"wx"` handler. §[Orca wrapper](#orca-webview-wrapper-widgetswebview)
-13. Do not widen `WEBKIT_DISABLE_COMPOSITING_MODE` beyond Orca's default-path XWayland case, and never
+13. Do not widen `WEBKIT_DISABLE_COMPOSITING_MODE` beyond Orca's default-path XWayland case for
+    WebKitGTK older than 2.42, and never
     make a page's progress depend only on a C++→JS callback. §[WebKitGTK on Linux](#webkitgtk-on-linux-sessions)
 14. GL attribute lists: legacy `int[]` lists end with `0` and spell out `WX_GL_RGBA` and
     `WX_GL_DOUBLEBUFFER`; `wxGLAttributes`/`wxGLContextAttrs` end with `EndList()`; MSAA is requested
@@ -567,33 +568,66 @@ vue-resize workaround script and sets a persistent SQLite cookie store on the vi
 ## WebKitGTK on Linux sessions
 
 **Mechanism.** `CLI::run` (`src/OrcaSlicer.cpp`, under `#ifdef __WXGTK__`, before GTK initialises)
-branches on `GDK_BACKEND`:
+sets the NVIDIA DMABUF workaround and then branches on `GDK_BACKEND`:
+- **Both paths**, before the split: when `/proc/driver/nvidia/version` exists and the linked WebKitGTK
+  honours the switch (>= 2.44, `WebView::SupportsForceSharedMemory()`), it sets
+  `WEBKIT_DMABUF_RENDERER_FORCE_SHM=1` and `WEBKIT_FORCE_DMABUF_RENDERER=1` non-replacing. The
+  proprietary driver cannot back WebKit's hardware DMABUF renderer, so the shared-memory transport keeps
+  accelerated compositing instead of dropping it; `WEBKIT_FORCE_DMABUF_RENDERER` clears the
+  Debian/Ubuntu/openSUSE `isNVIDIA()` early return, which otherwise returns before the FORCE_SHM check.
 - **Default path** (`GDK_BACKEND` unset or not starting with `x11`): if wx lacks EGL (`!wxHAS_EGL`) and
   `WAYLAND_DISPLAY` is set, it forces `GDK_BACKEND=x11`; it sets `WEBKIT_DISABLE_COMPOSITING_MODE=1`
-  non-replacing **only** when both `DISPLAY` and `WAYLAND_DISPLAY` are non-empty (a Wayland session with
+  non-replacing **only** when the linked WebKitGTK predates 2.42 (`WebView::NeedsCompositingWorkaround()`)
+  **and** both `DISPLAY` and `WAYLAND_DISPLAY` are non-empty (a Wayland session with
   XWayland available — the session, not the backend GTK will pick); `XInitThreads()` runs only when
   `DISPLAY` is set.
 - **`GDK_BACKEND=x11…` opt-in path**: sets `DRI_PRIME=1` (and the NVIDIA PRIME variables when
   `/proc/driver/nvidia/version` exists), calls `XInitThreads()`, and deliberately does **not** disable
-  compositing (the comment: the WebKit2GTK XWayland bug appears fixed in WebKit2GTK ≥ 2.42, and leaving
+  compositing, which keeps hardware acceleration for Device / Setup Wizard / login pages.
-  compositing on keeps hardware acceleration for Device / Setup Wizard / login pages).
 
 Runtime backend detection elsewhere uses Orca's `is_running_on_wayland()` / `is_running_on_x11()`
 (see `references/platforms.md`), not these environment variables.
 
 **Pitfall.**
+- **Rule:** On NVIDIA reach for `WEBKIT_DMABUF_RENDERER_FORCE_SHM` before
+  `WEBKIT_DISABLE_COMPOSITING_MODE`. **Why:** the proprietary driver cannot back WebKit's hardware
+  DMABUF renderer, leaving web views blank or slow; FORCE_SHM keeps accelerated compositing and only
+  skips the hardware path, while disabling compositing drops it. Threaded scrolling is a separate,
+  release-dependent default (off in 2.44/2.45, on from 2.46). `WEBKIT_DISABLE_DMABUF_RENDERER` is not a
+  substitute — it is read first, leaves the transport set empty (no compositing from 2.44 on, where the
+  X11/Wayland fallback renderers were removed) and has a reported crash path. On Debian/Ubuntu and
+  openSUSE the `isNVIDIA()` patch returns before the FORCE_SHM check, so `WEBKIT_FORCE_DMABUF_RENDERER=1`
+  must clear it first; that variable exists only in those patches. WebKit reads all of these once per
+  process, before the first WebView.
+  The test is `/proc/driver/nvidia/version`, so a hybrid laptop that renders on its iGPU also takes the
+  shared-memory path, which is a per-frame GPU readback rather than zero-copy; exporting
+  `WEBKIT_DMABUF_RENDERER_FORCE_SHM=0` in the environment restores the hardware path.
+  ```cpp
+  // Wrong: kills compositing and threaded scrolling (and can crash on modern WebKit)
+  ::setenv("WEBKIT_DISABLE_DMABUF_RENDERER", "1", false);
+  // Right: keep compositing, skip only the hardware DMABUF path
+  if (::access("/proc/driver/nvidia/version", F_OK) == 0 && WebView::SupportsForceSharedMemory()) {
+      ::setenv("WEBKIT_DMABUF_RENDERER_FORCE_SHM", "1", /*replace*/ false);
+      ::setenv("WEBKIT_FORCE_DMABUF_RENDERER", "1", /*replace*/ false);
+  }
+  ```
+  Cite: WebKit 2.52.6 `Source/WebKit/UIProcess/gtk/AcceleratedBackingStore.cpp`
+  (`rendererBufferTransportMode()`), Debian `disable-nvidia-dmabuf.patch`, WebKit bug 262607.
 - **Rule:** Set `WEBKIT_DISABLE_COMPOSITING_MODE` only on the default path in Wayland sessions,
   non-replacing (`setenv(..., false)`, so a value the user already exported wins), before GTK
-  initialises; never unconditionally. Keep JS-side fallbacks so a page never
+  initialises; never unconditionally, and only for the WebKitGTK releases that need it (older than
+  2.42, `WebView::NeedsCompositingWorkaround()`). Keep JS-side fallbacks so a page never
   waits forever for a C++→JS call.
-  **Why:** WebKit2GTK accelerated compositing could fail silently under XWayland, leaving web views
+  **Why:** WebKit2GTK accelerated compositing could fail silently under XWayland before 2.42, leaving
-  blank (Setup Wizard stuck on "Loading..."); disabling it everywhere needlessly drops hardware
+  web views blank (Setup Wizard stuck on "Loading..."); the variable also turns off threaded scrolling,
-  acceleration; without the JS timeout the user is stuck when the signal is lost.
+  so applying it on a newer WebKit needlessly drops both GPU compositing and async scrolling (the
+  Device tab loses its smoothness); without the JS timeout the user is stuck when the signal is lost.
   ```cpp
   // Wrong: unconditional, kills HW acceleration everywhere
   ::setenv("WEBKIT_DISABLE_COMPOSITING_MODE", "1", false);
-  // Right (default path only): non-replacing, before GTK init, Wayland session with XWayland
+  // Right (default path only): non-replacing, before GTK init, WebKitGTK < 2.42,
-  if (display && *display && wayland && *wayland)
+  // Wayland session with XWayland
+  if (WebView::NeedsCompositingWorkaround() && display && *display && wayland && *wayland)
       ::setenv("WEBKIT_DISABLE_COMPOSITING_MODE", "1", /*replace*/ false);
   ```
   Cite: c12912e0df (`src/OrcaSlicer.cpp`; `resources/web/guide/0/load.js` `OnInit`

scripts/flatpak/entrypoint

@@ -1,7 +1,7 @@
 #!/usr/bin/env sh
 
-# Work-around https://gitlab.gnome.org/GNOME/gnome-build-meta/-/issues/754
+# WebKit's NVIDIA DMABUF workaround (gnome-build-meta#754) is applied by the
-grep -q org.freedesktop.Platform.GL.nvidia /.flatpak-info && export WEBKIT_DISABLE_DMABUF_RENDERER=1
+# binary itself, gated on the runtime WebKitGTK version (src/OrcaSlicer.cpp).
 
 # Work-around https://github.com/bambulab/BambuStudio/issues/3440
 # Use LC_NUMERIC instead of LC_ALL to prevent decimal separator issues

src/OrcaSlicer.cpp

@@ -161,6 +161,7 @@ using json = nlohmann::json;
 #include <X11/Xlib.h>
 #endif
 #include <unistd.h>
+#include "slic3r/GUI/Widgets/WebView.hpp"
 #endif
 
 #ifdef SLIC3R_GUI
@@ -1153,8 +1154,9 @@ int CLI::run(int argc, char **argv)
     // opt-in path. The ~2020-era WebKit2GTK XWayland compositor bug it
     // worked around appears fixed in WebKit2GTK >= 2.42; leaving it
     // unset preserves WebKit hardware acceleration on Device / Setup
-    // Wizard / login / store. The default path still applies it on
+    // Wizard / login / store. The default path applies it only on
-    // XWayland sessions as a conservative fallback for older WebKit.
+    // XWayland sessions and only when the linked WebKitGTK predates the
+    // fix (< 2.42), as a conservative fallback for older WebKit.
     // ------------------------------------------------------------------
     {
         const char* gdk_backend = ::getenv("GDK_BACKEND");
@@ -1162,6 +1164,14 @@ int CLI::run(int argc, char **argv)
         // honours the first backend in the comma-separated list).
         const bool x11_opt_in = gdk_backend && boost::starts_with(gdk_backend, "x11");
 
+        // NVIDIA's proprietary driver cannot back WebKitGTK's DMABUF renderer.
+        // Force the shared-memory transport, which keeps compositing and threaded
+        // scrolling; the second variable clears Debian/Ubuntu/openSUSE's isNVIDIA().
+        if (::access("/proc/driver/nvidia/version", F_OK) == 0 && WebView::SupportsForceSharedMemory()) {
+            ::setenv("WEBKIT_DMABUF_RENDERER_FORCE_SHM", "1", /* replace */ false);
+            ::setenv("WEBKIT_FORCE_DMABUF_RENDERER", "1", /* replace */ false);
+        }
+
         if (x11_opt_in) {
             // ===== X11 / XWayland (opted in via GDK_BACKEND=x11) =====
             BOOST_LOG_TRIVIAL(info) << "GDK_BACKEND=x11 detected; applying v2.3.2 X11/XWayland workarounds.";
@@ -1205,15 +1215,15 @@ int CLI::run(int argc, char **argv)
             }
             #endif
 
-            // WebKit2GTK compositing can fail under XWayland on older
+            // WebKit2GTK accelerated compositing could fail under XWayland
-            // WebKit releases. Disable it only when both DISPLAY and
+            // on WebKit releases before 2.42. Disable it only then, and only
-            // WAYLAND_DISPLAY are set (i.e. an XWayland session is in
+            // when both DISPLAY and WAYLAND_DISPLAY are set (an XWayland
-            // use). On pure X11 or native Wayland, compositing is left
+            // session). Disabling it also turns off threaded scrolling, so on
-            // enabled so WebKit retains HW acceleration.
+            // newer WebKit it only costs performance.
             {
                 const char* display_env_wk = ::getenv("DISPLAY");
                 const char* wayland_env_wk = ::getenv("WAYLAND_DISPLAY");
-                if (display_env_wk && *display_env_wk && wayland_env_wk && *wayland_env_wk) {
+                if (WebView::NeedsCompositingWorkaround() && display_env_wk && *display_env_wk && wayland_env_wk && *wayland_env_wk) {
                     ::setenv("WEBKIT_DISABLE_COMPOSITING_MODE", "1", /* replace */ false);
                 }
             }

src/dev-utils/platform/unix/build_linux_image.sh.in

@@ -429,7 +429,8 @@ if [ "\$XDG_SESSION_TYPE" = "wayland" ] && [ "\$ZINK_DISABLE_OVERRIDE" != "1" ];
                 export __EGL_VENDOR_LIBRARY_FILENAMES=/usr/share/glvnd/egl_vendor.d/50_mesa.json
                 export MESA_LOADER_DRIVER_OVERRIDE=zink
                 export GALLIUM_DRIVER=zink
-                export WEBKIT_DISABLE_DMABUF_RENDERER=1
+                # WebKit's NVIDIA DMABUF workaround is applied by the binary itself,
+                # gated on the runtime WebKitGTK version (src/OrcaSlicer.cpp).
             fi
         fi
     fi

src/slic3r/GUI/Widgets/WebView.cpp

@@ -69,6 +69,10 @@ webkit_web_view_run_javascript_finish                (WebKitWebView
 						      GError                    **error);
 WEBKIT_API void
 webkit_javascript_result_unref              (WebKitJavascriptResult *js_result);
+WEBKIT_API guint
+webkit_get_major_version                     (void);
+WEBKIT_API guint
+webkit_get_minor_version                     (void);
 }
 #endif
 
@@ -401,6 +405,29 @@ bool WebView::NeedsRecreateOnShow()
     return false;
 #endif
 }
+
+bool WebView::NeedsCompositingWorkaround()
+{
+#ifdef __linux__
+    const guint major = webkit_get_major_version();
+    const guint minor = webkit_get_minor_version();
+    return major < 2 || (major == 2 && minor < 42);
+#else
+    return false;
+#endif
+}
+
+bool WebView::SupportsForceSharedMemory()
+{
+#ifdef __linux__
+    const guint major = webkit_get_major_version();
+    const guint minor = webkit_get_minor_version();
+    return major > 2 || (major == 2 && minor >= 44);
+#else
+    return false;
+#endif
+}
+
 #if wxUSE_WEBVIEW_EDGE
 bool WebView::CheckWebViewRuntime()
 {

src/slic3r/GUI/Widgets/WebView.hpp

@@ -30,6 +30,16 @@ public:
     // ignoring every navigation. A panel that gets true here recreates its view on first Show().
     static bool NeedsRecreateOnShow();
 
+    // True when the linked WebKitGTK predates 2.42, where accelerated compositing
+    // could fail silently on XWayland sessions, so it is forced off as a fallback.
+    // False on every other platform. Safe to call before GTK initialises.
+    static bool NeedsCompositingWorkaround();
+
+    // True when the linked WebKitGTK is new enough (>= 2.44) to honour
+    // WEBKIT_DMABUF_RENDERER_FORCE_SHM, the shared-memory transport switch.
+    // False on every other platform. Safe to call before GTK initialises.
+    static bool SupportsForceSharedMemory();
+
     static void RecreateAll();
 };