TableHeader: fixed missing trailing vertical separator line if used in upper left corner of scroll pane (issue #332)

CHANGELOG.md

@@ -26,6 +26,8 @@ FlatLaf Change Log
   regression since FlatLaf 1.4)
 - TableHeader: Do not show resize cursor for last column if resizing last column
   is not possible because auto resize mode of table is not off. (issue #332)
+- TableHeader: Fixed missing trailing vertical separator line if used in upper
+  left corner of scroll pane. (issue #332)
 - TextField, FormattedTextField, PasswordField and ComboBox: Fixed alignment of
   placeholder text in right-to-left component orientation.
 - Slider: Fixed calculation of baseline, which was wrong under some

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTableHeaderBorder.java

@@ -24,6 +24,7 @@ import java.awt.Graphics2D;
 import java.awt.geom.Rectangle2D;
 import javax.swing.JScrollBar;
 import javax.swing.JScrollPane;
+import javax.swing.JViewport;
 import javax.swing.SwingUtilities;
 import javax.swing.UIManager;
 import javax.swing.table.JTableHeader;
@@ -112,12 +113,20 @@ public class FlatTableHeaderBorder
 		if( showLastVerticalLine )
 			return false;
 
+		// do not hide if table header is not a child of a scroll pane
 		Container viewport = header.getParent();
 		Container viewportParent = (viewport != null) ? viewport.getParent() : null;
 		if( !(viewportParent instanceof JScrollPane) )
-			return true;
+			return false;
 
-		JScrollBar vsb = ((JScrollPane)viewportParent).getVerticalScrollBar();
+		// do not hide if table header is not the column header of the scroll pane
+		JScrollPane scrollPane = (JScrollPane) viewportParent;
+		JViewport columnHeader = scrollPane.getColumnHeader();
+		if( viewport != columnHeader )
+			return false;
+
+		// hide if vertical scroll bar is not shown
+		JScrollBar vsb = scrollPane.getVerticalScrollBar();
 		if( vsb == null || !vsb.isVisible() )
 			return true;
 

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTableUI.java

@@ -321,6 +321,7 @@ public class FlatTableUI
 		if( showLastVerticalLine )
 			return false;
 
+		// do not hide if table is not a child of a scroll pane
 		Container viewport = SwingUtilities.getUnwrappedParent( table );
 		Container viewportParent = (viewport != null) ? viewport.getParent() : null;
 		if( !(viewportParent instanceof JScrollPane) )