c++ - Drop shadow on masked window -

in project, have window has been masked setmask(qrect()). works fine, shadow window manager leaves gone. want drop shadow effect on program.

at first, moved of objects single widget , had widget cast box shadow onto mainwindow. made mainwindow transparent setattribute(qt::wa_translucentbackground, true) , setwindowflags(qt::framelesswindowhint). did job, however, having frameless window caused many issue can't seem fix. namely, this: https://stackoverflow.com/questions/31418494/qtframelesswindowhint-window-cant-be-recorded-with-obs

if setattribute(qt::wa_translucentbackground, true) or set style sheet, background becomes black, not transparent.

so question is, how make mainwindow transparent without removing frame? or how cast shadow when using setmask?

thanks time.