Kpsa4

There are already multiple versions compiled with QT5 and fully working on Win7. First one you can grab here: https://forum.videohelp.com/threads/405407-NON-OFFICIAL-Windows-builds-of-MKVtoolnix/page3#post2672418 Second one here: https://github.com/jpsdr/MKVToolnix-QT5-Windows-7 The first version seems to be updated regularly and available few hours or days after official release. It is opensource, so everybody can do this.

First unofficial build with QT5 for Win7/8.1 is here: https://forum.videohelp.com/threads/405407-NON-OFFICIAL-Windows-builds-of-MKVtoolnix-do-they-exist#post2663774

I've been able to run Calibre 6.1 on Windows 7 x64 using this method: 1. Download Calibre msi file from homepage and patch the installator using Orca to be able to install it on Win7 2. Copy and replace these QT6 Win7 compatible files from here: https://forum.qt.io/topic/133002/qt-creator-6-0-1-and-qt-6-2-2-running-on-windows-7 https://web.tresorit.com/l/iWnTl#yGMg45iqZObF8miEZt7FaA 3. Use VxKex to run Calibre