[EuiFocusTrap] Workaround for scrollLock prop causing nested portal…

…s/popovers to be unscrollable (#6744)

* Fix `scrollLock` causing nested popovers to be unable to scroll in Kibana

- using a workaround recommended by `react-focus-on`'s author

* Write Cypress e2e tests for scrollLock behavior

- to confirm that things are working as expected and try to prevent future regressions

* Add support for `gapMode`

- Kibana ignores `margin`, so we default to `padding` instead

* changelog

package.json

@@ -80,6 +80,7 @@
     "react-focus-on": "^3.7.0",
     "react-input-autosize": "^3.0.0",
     "react-is": "^17.0.2",
+    "react-remove-scroll-bar": "^2.3.4",
     "react-virtualized-auto-sizer": "^1.0.6",
     "react-window": "^1.8.6",
     "refractor": "^3.5.0",

src/components/focus_trap/focus_trap.spec.tsx

@@ -10,7 +10,7 @@
 /// <reference types="cypress-real-events" />
 /// <reference types="../../../cypress/support" />
 
-import React, { useRef } from 'react';
+import React, { useRef, useState } from 'react';
 import { EuiFocusTrap } from './focus_trap';
 import { EuiPortal } from '../portal';
 
@@ -235,4 +235,125 @@ describe('EuiFocusTrap', () => {
         });
     });
   });
+
+  describe('scrollLock', () => {
+    // TODO: Use cypress-real-event's `realMouseWheel` API, whenever they release it 🥲
+    const scrollSelector = (selector: string) => {
+      cy.get(selector).realClick({ position: 'topRight' }).realPress('End');
+      cy.wait(500); // Wait a tick to let scroll position update
+    };
+
+    // Control test to ensure Cypress isn't just giving us false positives for actual scrollLock tests
+    it('does not prevent scrolling on the body if not present', () => {
+      cy.realMount(
+        <div style={{ height: 2000 }}>
+          <EuiFocusTrap>Test</EuiFocusTrap>
+        </div>
+      );
+
+      scrollSelector('body');
+      cy.window().its('scrollY').should('not.equal', 0);
+    });
+
+    it('prevents scrolling on the page body', () => {
+      cy.realMount(
+        <div style={{ height: 2000 }}>
+          <EuiFocusTrap scrollLock>Test</EuiFocusTrap>
+        </div>
+      );
+
+      scrollSelector('body');
+      cy.window().its('scrollY').should('equal', 0);
+    });
+
+    it('allows nested portals to be scrolled', () => {
+      cy.realMount(
+        <div>
+          <EuiFocusTrap scrollLock>
+            Test
+            <EuiPortal>
+              <div
+                data-test-subj="scroll"
+                style={{ height: 100, overflow: 'auto' }}
+              >
+                <div style={{ height: 500 }}>Test</div>
+              </div>
+            </EuiPortal>
+          </EuiFocusTrap>
+        </div>
+      );
+
+      scrollSelector('[data-test-subj="scroll"]');
+      cy.get('[data-test-subj="scroll"]').then(($el) => {
+        expect($el[0].scrollTop).not.to.equal(0);
+      });
+    });
+
+    describe('scrollbar gap', () => {
+      const ToggledFocusTrap = (focusTrapProps: any) => {
+        const [isFocusTrapOpen, setIsFocusTrapOpen] = useState(false);
+
+        return (
+          <div style={{ height: 2000, backgroundColor: '#555' }}>
+            <button
+              data-test-subj="openFocusTrap"
+              onClick={() => setIsFocusTrapOpen(true)}
+            >
+              Toggle focus trap
+            </button>
+            {isFocusTrapOpen && (
+              <EuiFocusTrap scrollLock {...focusTrapProps}>
+                Test
+              </EuiFocusTrap>
+            )}
+          </div>
+        );
+      };
+
+      // Depending on the machine running these tests, scrollbars might not
+      // have a width (e.g. some Mac system settings) - if so, skip them
+      const skipIfNoScrollbars = () => {
+        cy.window().then((win) => {
+          const htmlWidth = Cypress.$('body')[0].scrollWidth;
+          const scrollBarWidth = win.innerWidth - htmlWidth;
+
+          if (scrollBarWidth === 0) {
+            cy.log('Skipping test - no scrollbars detected');
+            // @ts-ignore - this works even if Cypress doesn't type it
+            Cypress.mocha.getRunner().suite.ctx.skip();
+          }
+        });
+      };
+
+      it('preserves the scrollbar width when locked', () => {
+        cy.realMount(<ToggledFocusTrap />);
+        skipIfNoScrollbars();
+        cy.get('[data-test-subj="openFocusTrap"]').click();
+
+        cy.get('body').then(($body) => {
+          const styles = window.getComputedStyle($body[0]);
+
+          const padding = parseFloat(styles.getPropertyValue('padding-right'));
+          expect(padding).to.be.gt(0);
+
+          expect(styles.getPropertyValue('margin-right')).to.equal('0px');
+        });
+      });
+
+      it('allows customizing gapMode', () => {
+        cy.realMount(<ToggledFocusTrap gapMode="margin" />);
+        skipIfNoScrollbars();
+        cy.get('[data-test-subj="openFocusTrap"]').click();
+
+        cy.get('body').then(($body) => {
+          const styles = window.getComputedStyle($body[0]);
+
+          const margin = parseFloat(styles.getPropertyValue('margin-right'));
+          expect(margin).to.be.gt(0);
+
+          expect(styles.getPropertyValue('padding-right')).to.equal('0px');
+        });
+      });
+    });
+  });
 });

src/components/focus_trap/focus_trap.tsx

@@ -9,6 +9,7 @@
 import React, { Component, CSSProperties } from 'react';
 import { FocusOn } from 'react-focus-on';
 import { ReactFocusOnProps } from 'react-focus-on/dist/es5/types';
+import { RemoveScrollBar } from 'react-remove-scroll-bar';
 
 import { CommonProps } from '../common';
 import { findElementBySelectorOrRef, ElementTarget } from '../../services';
@@ -30,6 +31,12 @@ interface EuiFocusTrapInterface {
    */
   initialFocus?: FocusTarget;
   style?: CSSProperties;
+  /**
+   * if `scrollLock` is set to true, the body's scrollbar width will be preserved on lock
+   * via the `gapMode` CSS property. Depending on your custom CSS, you may prefer to use
+   * `margin` instead of `padding`.
+   */
+  gapMode?: 'padding' | 'margin';
   disabled?: boolean;
 }
 
@@ -49,6 +56,7 @@ export class EuiFocusTrap extends Component<EuiFocusTrapProps, State> {
     returnFocus: true,
     noIsolation: true,
     scrollLock: false,
+    gapMode: 'padding', // EUI defaults to padding because Kibana's body/layout CSS ignores `margin`
   };
 
   state: State = {
@@ -118,17 +126,28 @@ export class EuiFocusTrap extends Component<EuiFocusTrapProps, State> {
       returnFocus,
       noIsolation,
       scrollLock,
+      gapMode,
       ...rest
     } = this.props;
     const isDisabled = disabled || this.state.hasBeenDisabledByClick;
     const focusOnProps = {
       returnFocus,
       noIsolation,
-      scrollLock,
       enabled: !isDisabled,
       ...rest,
       onClickOutside: this.handleOutsideClick,
+      /**
+       * `scrollLock` should always be unset on FocusOn, as it can prevent scrolling on
+       * portals (i.e. popovers, comboboxes, dropdown menus, etc.) within modals & flyouts
+       * @see https://github.com/theKashey/react-focus-on/issues/49
+       */
+      scrollLock: false,
     };
-    return <FocusOn {...focusOnProps}>{children}</FocusOn>;
+    return (
+      <FocusOn {...focusOnProps}>
+        {children}
+        {scrollLock && <RemoveScrollBar gapMode={gapMode} />}
+      </FocusOn>
+    );
   }
 }

upcoming_changelogs/6744.md

@@ -0,0 +1,5 @@
+- Updated `EuiFocusTrap` to support the `gapMode` prop configuration (now defaults to `padding`)
+
+**Bug fixes**
+
+- Fixed the `scrollLock` property on `EuiFocusTrap` (and other components using `EuiFocusTrap`, such as `EuiFlyout` and `EuiModal`) to no longer block scrolling on nested portalled content, such as combobox dropdowns

yarn.lock

@@ -14450,7 +14450,7 @@ react-refresh@^0.11.0:
   resolved "https://registry.yarnpkg.com/react-refresh/-/react-refresh-0.11.0.tgz#77198b944733f0f1f1a90e791de4541f9f074046"
   integrity sha512-F27qZr8uUqwhWZboondsPx8tnC3Ct3SxZA3V5WyEvujRyyNv0VYPhoBg1gZ8/MV5tubQp76Trw8lTv9hzRBa+A==
 
-react-remove-scroll-bar@^2.3.3:
+react-remove-scroll-bar@^2.3.3, react-remove-scroll-bar@^2.3.4:
   version "2.3.4"
   resolved "https://registry.yarnpkg.com/react-remove-scroll-bar/-/react-remove-scroll-bar-2.3.4.tgz#53e272d7a5cb8242990c7f144c44d8bd8ab5afd9"
   integrity sha512-63C4YQBUt0m6ALadE9XV56hV8BgJWDmmTPY758iIJjfQKt2nYwoUrPk0LXRXcB/yIj82T1/Ixfdpdk68LwIB0A==