Regression (w/ fix): JFileChooser has irregular margins

[LoadingByte]

Consider the following minimal example, which draws a JFileChooser:

public class Main {
    public static void main(String[] args) {
        FlatLightLaf.setup();
        var frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.getContentPane().add(new JFileChooser());
        frame.pack();
        frame.setVisible(true);
    }
}

In FlatLaf 2.2, this works as expected: the component's margins are precisely dictated by the new EmptyBorder(12, 12, 11, 11) set up by MetalFileChooserUI. You can measure pixels to convince yourself:

Starting with FlatLaf 2.3 however, there are 8 superfluous pixels of margin on the right:

I'm pretty sure that the culprit is this section of code, which repackages the topPanel, filePane, and bottomPanel in a wrapper JPanel, but forgets about the getAccessoryPanel() (AP). In addition, it increases the hgap of JFileChooser's BorderLayout from 0 to 8 in preparation for FlatLaf's shortcuts panel. Now, seeing that the empty AP is not repackaged but remains subject to JFileChooser's top-level BorderLayout with the constraint LINE_END, it becomes clear why there are exactly 8 additional pixels on the right.

I think the most straightforward solution is to simply not forget the AP, i.e.:

			Component north = borderLayout.getLayoutComponent( BorderLayout.NORTH );
+			Component lineEnd = borderLayout.getLayoutComponent( BorderLayout.LINE_END );
			Component center = borderLayout.getLayoutComponent( BorderLayout.CENTER );
			Component south = borderLayout.getLayoutComponent( BorderLayout.SOUTH );
-			if( north != null && center != null && south != null ) {
+			if( north != null && lineEnd != null && center != null && south != null ) {
				JPanel p = new JPanel( new BorderLayout( 0, 11 ) );
				p.add( north, BorderLayout.NORTH );
+				p.add( lineEnd, BorderLayout.LINE_END );
				p.add( center, BorderLayout.CENTER );
				p.add( south, BorderLayout.SOUTH );
				fc.add( p, BorderLayout.CENTER );
			}

I've not tested this change myself, but I'm pretty certain it will resolve the issue.

Best,
Felix

[DevCharly]

Many thanks for the detailed report and the fix 👍

You're right, I forgot the (optional) accessory component.

This is the wrong layout of the accessory component in FlatLaf 2.3 - 2.5:

Fixed layout (same layout as in other Lafs and in FlatLaf 2.2 and older):