Steps to reproduce.
1 - Open Windows Explorer,
2 - Open multiple tabs of Windows Explorer in same window,
3 - Press close button of the window of Windows explorer,
4 - Result - closes only active tab.
Desired result: Should close the entire window (with all contained active tabs). If I want to close each tab individually I would do so in the close button of each tab.
IMPORTANT: This behaviour also occurs in grouped LibreOffice and grouped Microsoft Office instances.