can't change background color of tab when selected

[sugitatestblue]

New Issue Checklist

• [o ] Updated Tabman to the latest version
• [o ] I took a look at the Troubleshooting Guide
• [ o] I searched for existing GitHub issues

but not resolved https://github.com/uias/Tabman/issues/515

Issue Description

        barView.buttons.customize { (button) in
            button.backgroundView.style = .flat(color: .red)

but it is select/selected color

Other useful things

I want selectedBackgroundView and normal backgroundView

        barView.buttons.customize { (button) in
            button.backgroundView.style = .flat(color: .gray)
            button.selectedBackgroundView.style = .flat(color: .red)

[sugitatestblue]

How do I change the background when the button is selected and unselected? #522

[sugitatestblue]

fmm