How do I create a dropdown with a transparent background?

IntelliJ Platform
1

Hi, how do I set up a transparent background for a ComboBox or Button inside a ProjectViewPane?
By default it’s white rectangle; I would like to see just the text with the drop-down arrow.

scopeDropdown = ComboBox<ScopeDefinition>(scopes.toTypedArray<ScopeDefinition?>())
scopeDropdown.setSelectedItem(currentScope)
scopeDropdown.isOpaque = false // not working
scopeDropdown.setBorder(JBUI.Borders.empty());
scopeDropdown.background = JBUI.CurrentTheme.CustomFrameDecorations.paneBackground()

val refreshBtn = JButton(AllIcons.Actions.Refresh)
refreshBtn.setBorder(JBUI.Borders.empty());
refreshBtn.isOpaque = false
refreshBtn.background = JBUI.CurrentTheme.CustomFrameDecorations.paneBackground()

Is there a theme approach, style, classes or any presets?

3

I updated JetBrains IDEA and applied the Islands theme, and the issue no longer appears.