fix: Handle cross-window elements for OverflowTooltip

modules/react/tooltip/lib/OverflowTooltip.tsx

@@ -55,6 +55,11 @@ export const findEllipsisElement = (element: Element): Element | null => {
   }
 };
 
+const getInnerText = (element: Element): string => {
+  const ownerWindow = element.ownerDocument?.defaultView;
+  return ownerWindow && element instanceof ownerWindow.HTMLElement ? element.innerText : '';
+};
+
 const isOverflowed = (element: Element) => {
   const overflowElement = findEllipsisElement(element) || findOverflowElement(element);
 
@@ -134,14 +139,14 @@ export const OverflowTooltip = ({
 
   const onMouseEnter = (event: React.MouseEvent) => {
     const target = event.currentTarget;
-    setTitleText(target instanceof HTMLElement ? target.innerText : '');
+    setTitleText(getInnerText(target));
     if (isOverflowed(target)) {
       targetProps.onMouseEnter(event as React.MouseEvent);
     }
   };
   const onFocus = (event: React.FocusEvent) => {
     const target = event.currentTarget;
-    setTitleText(target instanceof HTMLElement ? target.innerText : '');
+    setTitleText(getInnerText(target));
     if (isOverflowed(target)) {
       targetProps.onFocus(event as React.FocusEvent);
     }

modules/react/tooltip/spec/OverflowTooltip.spec.tsx

@@ -1,4 +1,4 @@
-import {fireEvent, render, screen} from '@testing-library/react';
+import {fireEvent, render, screen, within} from '@testing-library/react';
 import {act} from 'react-dom/test-utils';
 
 import {OverflowTooltip, findEllipsisElement, findOverflowElement} from '..';
@@ -29,6 +29,7 @@ describe('OverflowTooltip', () => {
   const markAsOverflowed = (target: HTMLElement) => {
     Object.defineProperty(target, 'scrollWidth', {configurable: true, value: 200});
     Object.defineProperty(target, 'clientWidth', {configurable: true, value: 100});
+    Object.defineProperty(target, 'innerText', {configurable: true, value: target.textContent});
   };
 
   it('should render the tooltip after the delay when "showDelay" is passed', () => {
@@ -54,6 +55,57 @@ describe('OverflowTooltip', () => {
     expect(screen.getByRole('tooltip')).toBeInTheDocument();
   });
 
+  it('should show the target text in the tooltip when the target is overflowed', () => {
+    render(
+      <OverflowTooltip>
+        <span style={{overflow: 'hidden'}}>Overflowed Text</span>
+      </OverflowTooltip>
+    );
+
+    const target = screen.getByText('Overflowed Text');
+    markAsOverflowed(target);
+
+    fireEvent.mouseEnter(target);
+
+    act(() => {
+      vi.advanceTimersByTime(500);
+    });
+    expect(screen.getByRole('tooltip')).toHaveTextContent('Overflowed Text');
+  });
+
+  it('should show the target text when the target is in a different window realm', () => {
+    const testWindow = document.createElement('iframe');
+    document.body.appendChild(testWindow);
+
+    const containerBody = testWindow.contentDocument?.body;
+    if (!containerBody) {
+      throw new Error('iframe contentDocument not available');
+    }
+
+    const {unmount} = render(
+      <OverflowTooltip>
+        <span style={{overflow: 'hidden'}}>Overflowed Text</span>
+      </OverflowTooltip>,
+      {container: containerBody}
+    );
+
+    try {
+      const target = within(containerBody).getByText('Overflowed Text');
+      markAsOverflowed(target);
+
+      fireEvent.mouseEnter(target);
+
+      act(() => {
+        vi.advanceTimersByTime(500);
+      });
+      // Use textContent directly: toHaveTextContent() uses instanceof Node and fails across window realms
+      expect(within(containerBody).getByRole('tooltip').textContent).toBe('Overflowed Text');
+    } finally {
+      unmount();
+      testWindow.remove();
+    }
+  });
+
   it('should hide the tooltip after the delay when "hideDelay" is passed', () => {
     render(
       <OverflowTooltip hideDelay={300}>