Qt widgets camera examples doesn't handle missing camera input properly. Windows only allows one application to access a camera at a time.

Steps to reproduce:

•     Open the native windows camera application
•     Open the camera example (widget) - you should get a warning that the camera is not available
•     Press the Capture Photo button
•     Attempt to close the program - alt + f4 or by pressing the close button at the top right

Expected behavior:

The application should not display a camera feed as it is already being used in the native windows application.

Buttons should ideally be greyed out/not interactable until camera input is available.

The application should close normally.

Observed behavior:

All UI elements are still interactable.

When pressing the Capture Photo button:

All UI elements tone out/turn grey, the application refuses to shut down unless the process is killed manually or stopped in the debugger.

Equipment:

Logitech C920 HD Pro Webcam