ComboBox: paint focus border if combobox component itself is focused (instead of internal text field) or if client property JComponent.focusOwner is set

Theme Editor:
- do not set client property `JComponent.focusOwner` on internal components of combobox and spinner
- repaint preview on window activation (necessary because if something changed in editor and switching to another app, the editor is saved and the preview is updated while the editor window is not-active, which hides all focus indicators)

flatlaf-theme-editor/src/main/java/com/formdev/flatlaf/themeeditor/FlatThemeEditorPane.java

@@ -166,6 +166,11 @@ class FlatThemeEditorPane
 		scrollPane.getGutter().setLineNumberFont( font );
 	}
 
+	void windowActivated() {
+		if( preview != null )
+			preview.repaint();
+	}
+
 	@Override
 	public boolean requestFocusInWindow() {
 		return textArea.requestFocusInWindow();

flatlaf-theme-editor/src/main/java/com/formdev/flatlaf/themeeditor/FlatThemeFileEditor.java

@@ -148,6 +148,14 @@ class FlatThemeFileEditor
 		restoreState();
 		restoreWindowBounds();
 
+		addWindowListener( new WindowAdapter() {
+			@Override
+			public void windowActivated( WindowEvent e ) {
+				for( FlatThemeEditorPane themeEditorPane : getThemeEditorPanes() )
+					themeEditorPane.windowActivated();
+			}
+		} );
+
 		// load directory
 		if( dir == null ) {
 			String recentDirectory = state.get( KEY_RECENT_DIRECTORY, null );

flatlaf-theme-editor/src/main/java/com/formdev/flatlaf/themeeditor/FlatThemePreviewAll.java

@@ -188,8 +188,11 @@ class FlatThemePreviewAll
 		if( !isControlComponent( comp ) && comp instanceof JComponent )
 			((JComponent)comp).putClientProperty( FlatClientProperties.COMPONENT_FOCUS_OWNER, value );
 
-		if( !(comp instanceof Container) || comp instanceof JInternalFrame )
-			return;
+		if( !(comp instanceof Container) ||
+			comp instanceof JComboBox ||
+			comp instanceof JSpinner ||
+			comp instanceof JInternalFrame )
+		  return;
 
 		for( Component c : ((Container)comp).getComponents() ) {
 			if( c instanceof JScrollPane )