Help: Fix setting focus to help viewer

Change-Id: Ie846d6996298b74a4b55c359787fd4f63b471cdf
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/help/textbrowserhelpviewer.cpp

@@ -56,6 +56,7 @@ TextBrowserHelpViewer::TextBrowserHelpViewer(QWidget *parent)
     setLayout(layout);
     layout->setContentsMargins(0, 0, 0, 0);
     layout->addWidget(m_textBrowser, 10);
+    setFocusProxy(m_textBrowser);
     QPalette p = palette();
     p.setColor(QPalette::Inactive, QPalette::Highlight,
         p.color(QPalette::Active, QPalette::Highlight));