wayland: Always use exclusive fullscreen

Wayland does not allow clients to choose their own size and position
on the screen. The concept of fullscreening an application by sizing
it to the screen and removing decorations does not exist. Use
exclusive fullscreen instead.

src/yuzu/main.cpp

@@ -2915,9 +2915,14 @@ static QScreen* GuessCurrentScreen(QWidget* window) {
         });
 }
 
+bool GMainWindow::UsingExclusiveFullscreen() {
+    return Settings::values.fullscreen_mode.GetValue() == Settings::FullscreenMode::Exclusive ||
+           QGuiApplication::platformName() == QStringLiteral("wayland");
+}
+
 void GMainWindow::ShowFullscreen() {
-    const auto show_fullscreen = [](QWidget* window) {
-        if (Settings::values.fullscreen_mode.GetValue() == Settings::FullscreenMode::Exclusive) {
+    const auto show_fullscreen = [this](QWidget* window) {
+        if (UsingExclusiveFullscreen()) {
             window->showFullScreen();
             return;
         }
@@ -2945,7 +2950,7 @@ void GMainWindow::ShowFullscreen() {
 
 void GMainWindow::HideFullscreen() {
     if (ui->action_Single_Window_Mode->isChecked()) {
-        if (Settings::values.fullscreen_mode.GetValue() == Settings::FullscreenMode::Exclusive) {
+        if (UsingExclusiveFullscreen()) {
             showNormal();
             restoreGeometry(UISettings::values.geometry);
         } else {
@@ -2959,7 +2964,7 @@ void GMainWindow::HideFullscreen() {
         statusBar()->setVisible(ui->action_Show_Status_Bar->isChecked());
         ui->menubar->show();
     } else {
-        if (Settings::values.fullscreen_mode.GetValue() == Settings::FullscreenMode::Exclusive) {
+        if (UsingExclusiveFullscreen()) {
             render_window->showNormal();
             render_window->restoreGeometry(UISettings::values.renderwindow_geometry);
         } else {

src/yuzu/main.h

@@ -320,6 +320,7 @@ private slots:
     void OnDisplayTitleBars(bool);
     void InitializeHotkeys();
     void ToggleFullscreen();
+    bool UsingExclusiveFullscreen();
     void ShowFullscreen();
     void HideFullscreen();
     void ToggleWindowMode();