How to access a winapi that has a LPTSTR and maxlen param

	[DllImport('user32.dll', CharSet=CharSet.Auto, CallingConvention=CallingConvention.Winapi)] 

	public static extern int GetMenuString(IntPtr hMenu, uint uIDItem, [MarshalAs(UnmanagedType.LPTStr)]string lpString,int maxCount,uint uFlag);

	//Usage:
	String caption = new String(’t’, 30);//using a dummy char ‘t’ here.
	int len = GetMenuString(hsysmenu, commandID, caption, 30, 0));