macos: fullscreen mode can be changed at runtime

macos/Sources/Features/Terminal/TerminalController.swift

@@ -204,16 +204,45 @@ class TerminalController: BaseTerminalController
         // We need a window to fullscreen
         guard let window = self.window else { return }
 
-        // TODO: handle changing fullscreen modes at runtime
+        // If we have a previous fullscreen style initialized, we want to check if
-        // This is where we'd handle this.
+        // our mode changed. If it changed and we're in fullscreen, we exit so we can
-
+        // toggle it next time. If it changed and we're not in fullscreen we can just
-        // Initialize our style for the window. This may fail for various reasons so
+        // switch the handler.
-        // we also guard below.
+        let newStyle = mode.style(for: window)
-        if self.fullscreenStyle == nil {
+        old: if let oldStyle = self.fullscreenStyle {
-            self.fullscreenStyle = mode.style(for: window)
+            // If we're not fullscreen, we can nil it out so we get the new style
+            if !oldStyle.isFullscreen {
+                self.fullscreenStyle = nil
+                break old
             }
-        guard let fullscreenStyle else { return }
 
+            assert(oldStyle.isFullscreen)
+
+            // We consider our mode changed if the types change (obvious) but
+            // also if its nil (not obvious) because nil means that the style has
+            // likely changed but we don't support it.
+            if newStyle == nil || type(of: newStyle) != type(of: oldStyle) {
+                // Our mode changed. Exit fullscreen (since we're toggling anyways)
+                // and then unset the style so that we replace it next time.
+                oldStyle.exit()
+                self.fullscreenStyle = nil
+
+                // Fix our focus
+                if let focusedSurface {
+                    Ghostty.moveFocus(to: focusedSurface)
+                }
+
+                // We're done
+                return
+            }
+
+            // Style is the same.
+        } else {
+            // No old style, so set to our new style.
+            self.fullscreenStyle = newStyle
+        }
+
+        guard let fullscreenStyle else { return }
         if fullscreenStyle.isFullscreen {
             fullscreenStyle.exit()
         } else {

src/config/Config.zig

@@ -1384,6 +1384,9 @@ keybind: Keybinds = .{},
 ///   * `true` - Use non-native macOS fullscreen, hide the menu bar
 ///   * `false` - Use native macOS fullscreen
 ///
+/// Changing this option at runtime works, but will only apply to the next
+/// time the window is made fullscreen. If a window is already fullscreen,
+/// it will retain the previous setting until fullscreen is exited.
 @"macos-non-native-fullscreen": NonNativeFullscreen = .false,
 
 /// The style of the macOS titlebar. Available values are: "native",