The fact that the dialog ‘manage style’ is now modal is very unpractical because many times is needed to examine the document to get information needed to modify the styles.
Many many years ago, I stopped to use Windows also because I felt very upset by the many unpractical modal dialogs that I was receiving in Windows, now after using OpenOffice and after LibreOffice for many years I see modal dialog also here.
I really hope that there is a way to configure Writer and in general all-LibreOffice in way to minimize the number of modal dialogs or eventually to let all the dialog to be non-modal.