How to get a real Fullscreen - Windows / Linux NOT Borderless Fullscreen

[DEF]

Hi,
sf::Style::Fullscreen creates a borderless Fullscreen.

But how to get a proper exclusive Fullscreen under Windows / Linux?

My Code of Block for apply Vide looks like this ( i marked the corresponding line)

_{void UI::applyVideo() {
   if (gui.get<tgui::CheckBox>("Fullscreen", 1)->isChecked()) {
      if (options->currentmode == -1 || options->currentmode != gui.get<tgui::Slider>("VMSlider", 1)->getValue()) {
         options->currentmode = gui.get<tgui::Slider>("VMSlider", 1)->getValue();
         window->close();
         window->create(options->modes[options->currentmode], "SpeedBlocks", sf::Style::Fullscreen);
         window->setView(sf::View(sf::FloatRect(0, 0, 960, 600)));
         options->fullscreen=true;
      }
   }}