Fixed: #1044 Window content is black after switching windowed <-> fullscreen

code/nel/src/3d/driver/opengl/driver_opengl_window.cpp

@@ -1442,6 +1442,9 @@ bool CDriverGL::setWindowStyle(EWindowStyle windowStyle)
 	if (_win == EmptyWindow || !_DestroyWindow)
 		return true;
 
+	if (getWindowStyle() == windowStyle)
+		return true;
+
 #if defined(NL_OS_WINDOWS)
 
 	// get current style
@@ -1493,6 +1496,12 @@ bool CDriverGL::setWindowStyle(EWindowStyle windowStyle)
 
 #elif defined(NL_OS_UNIX)
 
+	XWindowAttributes attr;
+	XGetWindowAttributes(_dpy, _win, &attr);
+
+	// if window is mapped use events else properties
+	if (attr.map_state != IsUnmapped)
+	{
 		// Toggle fullscreen
 		XEvent xev;
 		xev.xclient.type = ClientMessage;
@@ -1512,6 +1521,24 @@ bool CDriverGL::setWindowStyle(EWindowStyle windowStyle)
 			nlwarning("3D: Failed to toggle to fullscreen");
 			return false;
 		}
+	}
+	else
+	{
+		Atom _NET_WM_STATE = XInternAtom(_dpy, "_NET_WM_STATE", False);
+
+		if (windowStyle == EWSFullscreen)
+		{
+			Atom _NET_WM_STATE_FULLSCREEN = XInternAtom(_dpy, "_NET_WM_STATE_FULLSCREEN", False);
+
+			// set state property to fullscreen
+			XChangeProperty(_dpy, _win, _NET_WM_STATE, XA_ATOM, 32, PropModeReplace, (const unsigned char*)&_NET_WM_STATE_FULLSCREEN, 1);
+		}
+		else
+		{
+			// delete state property
+			XDeleteProperty(_dpy, _win, _NET_WM_STATE);
+		}
+	}
 
 	// show window (hack to avoid black window bug)
 	if (_WindowVisible)