Title pane improvements (Windows 10 only)

[DevCharly]

This PR brings some improvements to the title pane used in (native) custom window decorations:

Right aligned components in title pane with embedded menu bar

A usual way to add a component to the right side of the menu bar is to first add a horizontal glue component (Box.createHorizontalGlue()) and then the own component. In a non-embedded menu bar it looks like this:

With this PR, this also works for embedded menu bars:

Example for adding own component to right side of menu bar:

JButton myButton = new JButton();
myButton.setIcon( new FlatSVGIcon( "myicon.svg" ) );
myButton.putClientProperty( "JButton.buttonType", "toolBarButton" );
myButton.setFocusable( false );
myMenuBar.add( Box.createHorizontalGlue() );
myMenuBar.add( myButton );

Window title now centered within window bounds

New: title centered between window bounds:

Old: title centered between menu bar and window buttons:

Left aligned title with embedded menu bar

Optionally left align title when menu bar is embedded:

Enable with:

UIManager.put( "TitlePane.centerTitleIfMenuBarEmbedded", false );

Center title

Optionally center title when menu bar is not embedded:

Enable with:

UIManager.put( "TitlePane.centerTitle", true );

Unified backgrounds

To give your app an even more modern look, you can now use unified backgrounds for window title bar, menu bar and main content. This is similar to what IntelliJ IDEA does.

Enable with:

UIManager.put( "TitlePane.unifiedBackground", true );

You can try this in the FlatLafDemo app with "Options > Unified Title Bar".