Added demo for tooltip.

src/test/java/ToolTipDemo.java

@@ -0,0 +1,47 @@
+import com.weis.darklaf.LafManager;
+import com.weis.darklaf.components.tooltip.ToolTipContext;
+
+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.MouseEvent;
+
+public class ToolTipDemo {
+
+    public static void main(final String[] args) {
+        SwingUtilities.invokeLater(() -> {
+            LafManager.install();
+            JFrame f = new JFrame();
+            var p = new JPanel();
+            p.add(new JButton("Button with very very long text") {
+                private final ToolTipContext context = new ToolTipContext(this);
+
+                {
+                    setToolTipText("ToolTip \n multiline \n third line's a charm");
+                }
+
+                @Override
+                protected void paintComponent(final Graphics g) {
+                    super.paintComponent(g);
+                    g.setColor(Color.RED);
+                    g.fillRect(getWidth() / 2, getHeight() / 2, 1, 1);
+                }
+
+                @Override
+                public JToolTip createToolTip() {
+                    return context.getToolTip();
+                }
+
+                @Override
+                public Point getToolTipLocation(final MouseEvent event) {
+                    return context.getToolTipLocation(event);
+                }
+
+
+            });
+            f.setContentPane(p);
+            f.setLocationRelativeTo(null);
+            f.setSize(100, 100);
+            f.setVisible(true);
+        });
+    }
+}