private void updateCloseButtons() {
			if( !scrollableTabLayoutEnabled() || !isShowCloseButton() || !isShowCloseButtonOnTab() )
				return;

			Color background = _tabPane.getBackground();

			for( int i = 0; i < _closeButtons.length; i++ ) {
				JButton closeButton = _closeButtons[i];
				if( closeButton.getWidth() == 0 || closeButton.getHeight() == 0 )
					continue; // not visible

				closeButton.setBounds( getTabCloseBounds( i ) );
				closeButton.setBackground( background );
			}
		}
Actually does nearly the same as super.paintContentBorder() but
  - not invoking paintContentBorder*Edge() methods
  - repaint selection
flatlaf-jide-oss/src/main/java/com/formdev/flatlaf/jideoss/ui/FlatJideTabbedPaneUI.java