Summary of the issue

A QML application which uses Qt VNC Server fails to execute by missing DLL when the application is built by MinGW tool chain. Same application runs without any problem when the application is built by MSVC. 

With further analysis, we realized the missing DLL was zlib1__.dll which Qt framework itself doesn't provide.

Steps to produce the issue

1. Have one sample QML application using Qt VNC Server.
2. Build the application for Desktop Windows MinGW target
3. Run the built application

Expected result

The application runs fine without any external special dependencies

Actual result

The application fails to run if zlib1__.dll is not on the system.

(zlib1__.dll file most likely stays under \Strawberry\c\bin)

I think the dependency to the DLL is generated by the configuration of the build environment for the module. It might be better to staticly link zlib.

For MSVC version, it seems zlib is not included in the built feature (QT_VNCSERVER_NO_ZLIB is choosen for the buit time configuration), as I can see QtVNCServer on MSVC built doesn't perform zlib compression for the streaming.