Fix key recording by setWindow before capture starts.

It is common that during the construction of widget, it is not yet added to
a window. Thus windowHandle will simply return null in this case. Always set
the window to before the capture starts.

BUG: 430388

src/kkeysequencewidget.cpp

@@ -493,6 +493,7 @@ void KKeySequenceWidget::setCheckActionCollections(const QList<KActionCollection
 //slot
 void KKeySequenceWidget::captureKeySequence()
 {
+    d->recorder->setWindow(window()->windowHandle());
     d->recorder->startRecording();
 }