diff --git a/src/ui/win_dwm.py b/src/ui/win_dwm.py
new file mode 100644
index 0000000..9cceb33
--- /dev/null
+++ b/src/ui/win_dwm.py
@@ -0,0 +1,12 @@
+import ctypes
+from sys import platform
+
+def enable_blur_behind(hwnd: int) -> None:
+    """Force DWM à activer la composition derrière la fenêtre."""
+    if not platform.startswith('win'):
+        return
+    try:
+        margins = (ctypes.c_int * 4)(-1, -1, -1, -1)
+        ctypes.windll.dwmapi.DwmExtendFrameIntoClientArea(hwnd, ctypes.byref(margins))
+    except Exception:
+        pass  # Silencieux si DWM indisponible