<Swing Dev> RFR: 4916923: In MetalRootPaneUI, MetalRootLayout does not correctly calculate minimumsize

[Prasanta Sadhukhan]

On Sat, 10 Oct 2020 11:33:57 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> I tried following testcase snippet
>>                ```
>>  JRootPane r = new JRootPane();
>>                 JFrame f = new JFrame();
>>                 f.getRootPane().setUI(new MetalRootPaneUI());
>>                 f.getRootPane().setWindowDecorationStyle(JRootPane.FRAME);
>>                 f.getRootPane().getUI().installUI(r);
>>                 r.getContentPane().add(new JLabel("foo"));
>>                 System.out.println("Preferred Size: " + r.getPreferredSize());
>> but it uses JRootPane.RootLayout layout manager and not MetalRootLayout so it calls Rootlayout.preferredLayoutSize and not MetalRootLayout.preferredlayoutSize
>
> You need to set decorations for the root pane:
>         UIManager.setLookAndFeel(new MetalLookAndFeel());
>         JFrame frame = new JFrame();
>         frame.getRootPane().setWindowDecorationStyle(JRootPane.FRAME);
>         frame.pack();
>         System.out.println("Layout: " + frame.getRootPane().getLayout());
> ========
> Layout: javax.swing.plaf.metal.MetalRootPaneUI$MetalRootLayout at 69d9c55

I tried with 
 UIManager.setLookAndFeel(new MetalLookAndFeel());
JFrame frame = new JFrame();
                frame.setSize(new Dimension(500, 800));
                frame.getRootPane().setWindowDecorationStyle(JRootPane.FRAME);
                //frame.pack();
                frame.setVisible(true);
                System.out.println("Layout: " + frame.getRootPane().getLayout());
                System.out.println("PreferredSize " + frame.getRootPane().getPreferredSize());
but it seems tpWidth and tpHeight what is being changed is the width and height of MetalTitlePane which seems always comes as 23 for both no matter what frame size is set, so I guess using any variable will do but logically, it will be good to use "tpHeight" for height calculation.
If it is believed to continue with same logical but not technical error, I will close this PR without integrating.

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PR: https://git.openjdk.java.net/jdk/pull/433