The trueSKY plugin for Unreal uses Qt dll's for UI. Unfortunately so do some other plugins. Because Windows just uses whichever version of a dll was loaded first, this leads to (for example) crashes in trueSKY UI because it tries to access the wrong parts of a dll loaded by Quixel Megascans.
To solve this we recompile Qt using the switch -qtlibinfix to modify the output filenames. Thus instead of Qt5Core.dll we get Qt5Core_simul.dll etc.
No more conflicts!
UPDATE: To compile Qt, follow the instructions at https://wiki.qt.io/Building_Qt_5_from_Git. For example, for me on Windows, I must git-clone the repo, install perl (!) and call perl init-repository.
Then, I create a subdirectory BUILD_DIR at subdirectory "build/x64". From there, I call:
call ../../configure.bat -qtlibinfix %QT_INFIX% -prefix %BUILD_DIR%\qtbase -skip qtwebengine -developer-build -%reldeb% -force-debug-info -no-warnings-are-errors -L kernel32 -opengl desktop -opensource -make libs -make tools -nomake examples -nomake tests -platform win32-msvc -confirm-license -no-compile-examples -qt-zlib -plugin-manifests -no-angle -qt-freetype -qt-libjpeg -qt-libpng -D U_STATIC_IMPLEMENTATION %INC% %LIBDIRS% %IC%
QT_INFIX is _simul, while INC LIBDIRS and IC are extra compile options.
Finally, we run nMake to build Qt.
