Qt 5.6.1 The interface cannot be displayed either by double-clicking the UI file in VS or by launching Designer.exe directly, but you can see that the process exists in Task Manager. A few days ago, but yesterday added an Nvidia graphics card (the machine comes with a nuclear display), it may be related to this. Fortunately, you can also open the UI file for editing by Qtcreator.
Found the corresponding QT bug but still open ... The address is as follows: https://bugreports.qt.io/browse/QTBUG-53984
According to the bug description should be in the case of WIN10 64-bit system and is a dual graphics card, Qt5WebEngineWidgets.dll will be stuck when the designer starts, resulting in the designer never display the interface.
For the reasons above, the solutions are as follows:
1. Replace with Qtcreator
2. Renaming Qt5WebEngineWidgets.dll
3, QT replacement for 5.6.0
4, encoding without the Nvidia graphics card (theory is feasible, not tested)
5, and other bug fixes after the version
6. Find the code of the problem yourself, modify the compilation Yourself
Choose one of the above options, I chose the scheme 1, anyway, not commonly used designer, waiting for the program 5 or a burst of need to customize QT code, the problem changed (program 6). There should be no other feasible solution, if there is, welcome to reply, thank you!
Reasons and solutions of not displaying interface problems after QT designer starts