a suggest: support dynamic define variable mechanism for window instance
Created by: 10km
In my project, base mgncs, I design a dynamic define variable mechanism for a mWidget instance ,so called "Widget Local",
see my blog for detail : https://blog.csdn.net/10km/article/details/81666413 .
I think it's a useful feature for general application design. Although my code is base mgncs,but it's easy to modify for minigui , if you think necessary ,I can contribute it for minigui. also if minigui have implemented alternative mechanism , please tell me.