[ BUG ] Detached window (project monitor,etc) looses title bar

Operating System: Antergos Linux

KDE Plasma Version: 5.16.5

KDE Frameworks Version: 5.62.0

Qt Version: 5.13.1

Kernel Version: 5.2.14-arch2-1-ARCH

Kdenlive version: master branch (02/10/19) 19.11.80

similar issue: https://invent.kde.org/kde/kdenlive/issues/234