Close independent windows and close other windows at the same time

If you set QMainWindow Of flag Attributes are Qt::Tool, As long as an independent window appears in the program , When the independent window is closed QMainWindow It will also be shut down

resolvent ：

1 Set the parent object of the independent window to QMainWindow

2 Not set up QMainWindow Of flag Attributes are Qt::Tool

3 Don't use QMainWindow window , Use other QWidget window