@Override
	public Insets getBorderInsets( Component c, Insets insets ) {
		Container parent = c.getParent();
		if( parent instanceof JMenuBar ) {
			// get margins from FlatMenuBarUI to allow styling
			MenuBarUI ui = ((JMenuBar)parent).getUI();
			Insets margins = (ui instanceof FlatMenuBarUI && ((FlatMenuBarUI)ui).itemMargins != null)
				? ((FlatMenuBarUI)ui).itemMargins
				: this.menuBarItemMargins;
			insets.top = scale( margins.top );
			insets.left = scale( margins.left );
			insets.bottom = scale( margins.bottom );
			insets.right = scale( margins.right );
			return insets;
		} else
			return super.getBorderInsets( c, insets );
	}
Border for {@link javax.swing.JMenu}, {@link javax.swing.JMenuItem},
{@link javax.swing.JCheckBoxMenuItem} and {@link javax.swing.JRadioButtonMenuItem}.

@uiDefault MenuBar.itemMargins				Insets

@author Karl Tauber
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatMenuItemBorder.java