Clear the Qwidget window using window id

[Dcqt]

Hi,

Is there any way to clear/refresh the window (QWidget) by making use of window id.
this is the code i am using.

Please help.

Process1:
@
QX11EmbedContainer *Cont = new QX11EmbedContainer;
qDebug()<<"Cont Addr"<<Cont;
QProcess *Proc1 = new QProcess(Cont);
QStringList Arguments;
Arguments<QString::number(Cont-windId());
Proc1->start(someappproc, Arguments);
@

Process2:

@
QApplication qApp(argc, argv);
QString s_WinId(qApp.arguments()[1]);
WId l_WinId = sWinId.toLong();
QWidget *temp = QWidget ::find(l_Winid);
qDebug()<<"temp Addr"<<temp;
@

The problem i am facing is , some times the contents(images/video) displayed on the window are not cleared even though the application is terminated.
I thought of accessing the address and try to use QPalette or something to change the color to black so that the window is cleared, but i am not able to access it from another process , and we cannot do that, i referred from here
http://stackoverflow.com/questions/17319853/can-qwidgetfind-find-widgets-from-a-different-process
i would like to clear the contents displayed on the window using the s_WinId or l_WinId.

i found that in the application side they are using "gst_x_overlay_set_window_handle" to embed a window inside another, is there any function available to clear the window using window Id.

[Dcqt]

Any suggestion on this please....