Fix SEGV caused by null parent widget. This solves issue #2.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>

style/polyester.cpp

@@ -4620,7 +4620,7 @@ bool PolyesterStyle::eventFilter(TQObject *obj, TQEvent *ev)
     if ( obj->inherits("TQLineEdit") ) {
         TQWidget* widget = static_cast<TQWidget*>(obj);
 
-        if ( widget->parentWidget()->inherits("TQSpinWidget") )
+        if ( widget->parentWidget() && widget->parentWidget()->inherits("TQSpinWidget") )
         {
             TQWidget* spinbox = widget->parentWidget();
             if ((ev->type() == TQEvent::FocusIn) || (ev->type() == TQEvent::FocusOut))