Qt virtualkeyboard doesn't show the text input in the backgorund

[Kart]

I have a simple lineEdit in my widget. Where i need to input my text via the virtualkeyboard. I am using Qt 5.9.1.

main.cpp

int main(int argc, char *argv[])
{
    qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard"));
    QApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}

I am running this code on a x86 32 bit processor which only have linuxfb.
The widget is working fine except that when i click on the input area the keyboard pops up and nothing else is viewable. When i close the keyboard, the entered words are successfully placed in the input area.

I am also getting a warning which says,This plugin does not support setting window masks.
Is there any work around for this issue or did i miss adding any support for the plugin during Qt build ?