Align fullscreen return button with project actions

electron/main/ipc/window-fullscreen.ts

@@ -0,0 +1,20 @@
+import { ipcMain, type BrowserWindow } from 'electron';
+
+export function registerWindowFullscreenHandlers(
+  requireWindow: (event: Electron.IpcMainInvokeEvent) => BrowserWindow,
+): (window: BrowserWindow) => void {
+  ipcMain.handle('window:isFullScreen', (event) => requireWindow(event).isFullScreen());
+
+  const boundWindows = new WeakSet<BrowserWindow>();
+  return (window: BrowserWindow): void => {
+    if (window.isDestroyed() || window.webContents.isDestroyed() || boundWindows.has(window)) return;
+    boundWindows.add(window);
+
+    const notify = (fullscreen: boolean): void => {
+      if (window.isDestroyed() || window.webContents.isDestroyed()) return;
+      window.webContents.send('window:fullscreen-changed', fullscreen);
+    };
+    window.on('enter-full-screen', () => notify(true));
+    window.on('leave-full-screen', () => notify(false));
+  };
+}