Mouse events synthesized from touch events doesn't get grabbed correctly.

The problem can easily be tested with this example:

#include <QLineEdit>
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);	
    QLineEdit edit("Hello world !");
    edit.show();
    return app.exec();
}

Selecting the text with touch input and then dragging outside the window will not change the selection as you move up or down to select the entire row. But it will with the --platform windows:nowmpointer.