fix: gnome margin visual bug

src/Gui/Network/TabMenu.cpp

@@ -320,6 +320,8 @@ enzo::ui::TabMenuButton::TabMenuButton(const QString &text, QWidget *parent)
     icon_->setFixedSize(16, 16);
 
     mainLayout_ = new QHBoxLayout();
+    constexpr int leftRightMargin = 10;
+    mainLayout_->setContentsMargins(leftRightMargin,0,leftRightMargin,0);
 
     mainLayout_->addWidget(icon_);
     mainLayout_->addWidget(textLabel_);

src/Gui/Parameters/FloatSliderParm.cpp

@@ -21,6 +21,7 @@ enzo::ui::FloatSliderParm::FloatSliderParm(std::weak_ptr<prm::Parameter> paramet
     parameter_ = parameter;
     
     mainLayout_ = new QVBoxLayout();
+    mainLayout_->setContentsMargins(0,0,0,0);
     setLayout(mainLayout_);
 
     valueLabel_ = new QLabel();

src/Gui/Parameters/IntSliderParm.cpp

@@ -25,6 +25,7 @@ enzo::ui::IntSliderParm::IntSliderParm(std::weak_ptr<prm::Parameter> parameter,
     parameter_=parameter;
 
     mainLayout_ = new QVBoxLayout();
+    mainLayout_->setContentsMargins(0,0,0,0);
     setLayout(mainLayout_);
 
     valueLabel_ = new QLabel();

src/Gui/main.cpp

@@ -15,9 +15,9 @@ int main(int argc, char **argv)
     format.setSamples(4);
     QSurfaceFormat::setDefaultFormat(format);
 
+    // init plugins
     enzo::op::OperatorTable::initPlugins();
 
-
     QApplication app (argc, argv);
 
     EnzoUI interface;