In the GUI, if you right click on the tabs at the top, a menu appears with a checkbox item that says `Tabs Toolbar`. Clicking that makes the tabs at the top disappear. However there is no way for the tabs to be brought back except by restarting the software.

IMO it really isn't useful to hide the tabs and I'm not sure if there is an easy way to make a menu which brings them back.
receiveCoinsMenuAction->setToolTip(receiveCoinsMenuAction->statusTip());
    historyAction = new QAction(platformStyle->SingleColorIcon(":/icons/history"), tr("&Transactions"), this);
    historyAction->setStatusTip(tr("Browse transaction history"));
    historyAction->setToolTip(historyAction->statusTip());
    historyAction->setCheckable(true);
    historyAction->setShortcut(QKeySequence(Qt::ALT + Qt::Key_4));
    tabGroup->addAction(historyAction);
#ifdef ENABLE_WALLET
    
    
    connect(overviewAction, SIGNAL(triggered()), this, SLOT(showNormalIfMinimized()));
    connect(overviewAction, SIGNAL(triggered()), this, SLOT(gotoOverviewPage()));
    connect(sendCoinsAction, SIGNAL(triggered()), this, SLOT(showNormalIfMinimized()));
    connect(sendCoinsAction, SIGNAL(triggered()), this, SLOT(gotoSendCoinsPage()));
    connect(sendCoinsMenuAction, SIGNAL(triggered()), this, SLOT(showNormalIfMinimized()));
    connect(sendCoinsMenuAction, SIGNAL(triggered()), this, SLOT(gotoSendCoinsPage()));
    connect(receiveCoinsAction, SIGNAL(triggered()), this, SLOT(showNormalIfMinimized()));
    connect(receiveCoinsAction, SIGNAL(triggered()), this, SLOT(gotoReceiveCoinsPage()));
    connect(receiveCoinsMenuAction, SIGNAL(triggered()), this, SLOT(showNormalIfMinimized()));
    connect(receiveCoinsMenuAction, SIGNAL(triggered()), this, SLOT(gotoReceiveCoinsPage()));
    connect(historyAction, SIGNAL(triggered()), this, SLOT(showNormalIfMinimized()));
    connect(historyAction, SIGNAL(triggered()), this, SLOT(gotoHistoryPage()));
#endif 
    quitAction = new QAction(platformStyle->TextColorIcon(":/icons/quit"), tr("E&xit"), this);
    quitAction->setStatusTip(tr("Quit application"));
    quitAction->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_Q));
    quitAction->setMenuRole(QAction::QuitRole);
    aboutAction = new QAction(platformStyle->TextColorIcon(":/icons/about"), tr("&About %1").arg(tr(PACKAGE_NAME)), this);
    aboutAction->setStatusTip(tr("Show information about %1").arg(tr(PACKAGE_NAME)));
    aboutAction->setMenuRole(QAction::AboutRole);