src/vs/platform/windows/electron-main/window.ts/CodeWindow/handleTitleDoubleClick
class CodeWindow:	handleTitleDoubleClick(): void {

		// Respect system settings on mac with regards to title click on windows title
		if (isMacintosh) {
			const action = systemPreferences.getUserDefault('AppleActionOnDoubleClick', 'string');
			switch (action) {
				case 'Minimize':
					this._win.minimize();
					break;
				case 'None':
					break;
				case 'Maximize':
				default:
					if (this._win.isMaximized()) {
						this._win.unmaximize();
					} else {
						this._win.maximize();
					}
			}
		}

		// Linux/Windows: just toggle maximize/minimized state
		else {
			if (this._win.isMaximized()) {
				this._win.unmaximize();
			} else {
				this._win.maximize();
			}
		}
	}