Unsolved Waiting gif transparent on QDialog

[Abdurahman_Gulamkadirov]

Hi there! I'm making a simple program that requests to API, while waiting for response, it should show transparent waiting gif with blurry background. When request is sent, I set blur graphics effect to my MainWindow, and call frameless QDialog. On my QDialog, there's just a label that should play the waiting gif. My problem is that background of gif is transparent. I tried some ways: changing style sheet background-color: transparent; of both label and dialog, but there's no result. I also tried palette:

pal.setColor(QPalette::Background, QColor(0x00,0xff,0x00,0x00));
setPalette(pal);

but background is black, it doesn't turn into transparent, what do you advice?

P.S: Sorry, my english is not good