QScrollArea with transparent background

I would like to check if I'm doing it correctly. Advises are welcome.

I have a set o widgets which I want to layout horizontally, as they are many and occupies lot of space I use a QScrollArea to accommodate them.

Then I put the QWidget which has the QScrollArea in another QWidget.

And finally, that last QWidget is inserted in a QTabWidget.

The problem I see is:

The tabWidget has a white background and the scrollAreaWidgetContents has a gray background. With the intention of solve this I tried ui->scrollAreaWidgetContents->setAttribute(Qt::WA_TranslucentBackground), but all the scrollArea contents get trashed when moving the scroll.

What exactly is the effect you want to obtain? Do you wish to get rid of the gray background?

Yes, exactly.

Did you try setting the background color to Qt::Transparent or making sure autofillBackground is set to false? In general I tried to repeat the problem you are having using Qt Designed but everything works for me as expected. Can you provide a minimal compilable example reproducing the problem?

Please find a compilable example attached.

I tried both. Setting the background color to Qt::Transparent makes even the buttons and scrollbar transparent, which I didn't want.