Explicitly use QTabBar scroll buttons

Even though QTabBar's property usesScrollButtons is set to true in Qt
Designer, it is not set explicitly in generated C++ code. The default
value is style dependent, which caused the scroll buttons to be visibile
everywhere except Mac OS/X.

refs #683

src/blackgui/components/aircraftcomponent.cpp

@@ -44,6 +44,7 @@ namespace BlackGui
         {
             ui->setupUi(this);
             this->tabBar()->setExpanding(false);
+            this->tabBar()->setUsesScrollButtons(true);
             this->ui->tvp_AirportsInRange->setResizeMode(CAirportView::ResizingOnce);
 
             this->ui->tvp_AircraftInRange->setAircraftMode(CSimulatedAircraftListModel::InfoMode);

src/blackgui/components/atcstationcomponent.cpp

@@ -57,6 +57,7 @@ namespace BlackGui
         {
             ui->setupUi(this);
             this->tabBar()->setExpanding(false);
+            this->tabBar()->setUsesScrollButtons(true);
 
             // some icons
             this->ui->pb_AtcStationsAtisReload->setIcon(CIcons::atis());

src/blackgui/components/flightplancomponent.cpp

@@ -65,6 +65,7 @@ namespace BlackGui
 
             // fix style
             this->tabBar()->setExpanding(false);
+            this->tabBar()->setUsesScrollButtons(true);
 
             // validators
             CUpperCaseValidator *ucv = new CUpperCaseValidator(this);

src/blackgui/components/mappingcomponent.cpp

@@ -38,8 +38,6 @@
 #include <QPixmap>
 #include <QPushButton>
 #include <QStringListModel>
-#include <QTabBar>
-#include <QTabWidget>
 #include <QtGlobal>
 
 using namespace BlackMisc;

src/blackgui/components/settingscomponent.cpp

@@ -44,6 +44,7 @@ namespace BlackGui
         {
             ui->setupUi(this);
             this->tabBar()->setExpanding(false);
+            this->tabBar()->setUsesScrollButtons(true);
 
             // Opacity, intervals
             this->connect(this->ui->hs_SettingsGuiOpacity, &QSlider::valueChanged, this, &CSettingsComponent::changedWindowsOpacity);

src/blackgui/components/usercomponent.cpp

@@ -36,6 +36,7 @@ namespace BlackGui
         {
             ui->setupUi(this);
             this->tabBar()->setExpanding(false);
+            this->tabBar()->setUsesScrollButtons(true);
             connect(this->ui->tvp_AllUsers, &CUserView::modelDataChanged, this, &CUserComponent::ps_onCountChanged);
             connect(this->ui->tvp_Clients, &CClientView::modelDataChanged, this, &CUserComponent::ps_onCountChanged);
             connect(sGui->getIContextNetwork(), &IContextNetwork::connectionStatusChanged, this, &CUserComponent::ps_connectionStatusChanged);

src/blackgui/infoarea.cpp

@@ -537,6 +537,7 @@ namespace BlackGui
                 this->m_tabBar->setObjectName("comp_MainInfoAreaDockWidgetTab");
                 this->m_tabBar->setMovable(false);
                 this->m_tabBar->setElideMode(Qt::ElideNone);
+                this->m_tabBar->setUsesScrollButtons(true);
 
                 // East / West does not work (shown, but area itself empty)
                 // South does not have any effect