Tabs: tweak sizing and overflow behavior of TabList

packages/block-editor/src/components/inserter/style.scss

@@ -257,39 +257,11 @@ $block-inserter-tabs-height: 44px;
 			svg {
 				fill: var(--wp-admin-theme-color);
 			}
-
-			&::after {
-				content: "";
-				display: block;
-				outline: none;
-				position: absolute;
-				top: 0;
-				bottom: 0;
-				left: 0;
-				right: 0;
-				border-radius: $radius-small;
-				opacity: 0.04;
-				background: var(--wp-admin-theme-color);
-				height: 100%;
-			}
-		}
-
-		&:focus-visible,
-		&:focus:not(:disabled) {
-			border-radius: $radius-small;
-			box-shadow: 0 0 0 var(--wp-admin-border-width-focus) var(--wp-admin-theme-color);
-			// Windows high contrast mode.
-			outline: 2px solid transparent;
-			outline-offset: 0;
 		}
 
 		&::before {
 			display: none;
 		}
-
-		&::after {
-			display: none;
-		}
 	}
 }
 

packages/block-editor/src/components/inspector-controls-tabs/style.scss

@@ -1,7 +1,3 @@
-.show-icon-labels {
-	.block-editor-block-inspector__tabs [role="tablist"] {
-		.components-button {
-			justify-content: center;
-		}
-	}
+.block-editor-block-inspector__tabs [role="tablist"] {
+	width: 100%;
 }

packages/components/CHANGELOG.md

@@ -14,6 +14,7 @@
 
 ### Enhancements
 
+-   `Tabs`: handle horizontal overflow and large tab lists gracefully ([#64371](https://github.com/WordPress/gutenberg/pull/64371)).
 -   `BorderBoxControl`: promote to stable ([#65586](https://github.com/WordPress/gutenberg/pull/65586)).
 -   `MenuGroup`: Simplify the MenuGroup styles within dropdown menus. ([#65561](https://github.com/WordPress/gutenberg/pull/65561)).
 -   `DatePicker`: Use compact button size. ([#65653](https://github.com/WordPress/gutenberg/pull/65653)).

packages/components/src/tabs/stories/index.story.tsx

@@ -70,6 +70,112 @@ const Template: StoryFn< typeof Tabs > = ( props ) => {
 
 export const Default = Template.bind( {} );
 
+export const SizeAndOverflowPlayground: StoryFn< typeof Tabs > = ( props ) => {
+	const [ fullWidth, setFullWidth ] = useState( false );
+	return (
+		<div>
+			<div style={ { maxWidth: '40rem', marginBottom: '1rem' } }>
+				<p>
+					This story helps understand how the TabList component
+					behaves under different conditions. The container below
+					(with the dotted red border) can be horizontally resized,
+					and it has a bit of padding to be out of the way of the
+					TabList.
+				</p>
+				<p>
+					The button will toggle between full width (adding{ ' ' }
+					<code>width: 100%</code>) and the default width.
+				</p>
+				<p>Try the following:</p>
+				<ul>
+					<li>
+						<strong>Small container</strong> that causes tabs to
+						overflow with scroll.
+					</li>
+					<li>
+						<strong>Large container</strong> that exceeds the normal
+						width of the tabs.
+						<ul>
+							<li>
+								<strong>
+									With <code>width: 100%</code>
+								</strong>{ ' ' }
+								set on the TabList (tabs fill up the space).
+							</li>
+							<li>
+								<strong>
+									Without <code>width: 100%</code>
+								</strong>{ ' ' }
+								(defaults to <code>auto</code>) set on the
+								TabList (tabs take up space proportional to
+								their content).
+							</li>
+						</ul>
+					</li>
+				</ul>
+			</div>
+			<Button
+				style={ { marginBottom: '1rem' } }
+				variant="primary"
+				onClick={ () => setFullWidth( ! fullWidth ) }
+			>
+				{ fullWidth
+					? 'Remove width: 100% from TabList'
+					: 'Set width: 100% in TabList' }
+			</Button>
+			<Tabs { ...props }>
+				<div
+					style={ {
+						width: '20rem',
+						border: '2px dotted red',
+						padding: '1rem',
+						resize: 'horizontal',
+						overflow: 'auto',
+					} }
+				>
+					<Tabs.TabList
+						style={ {
+							maxWidth: '100%',
+							width: fullWidth ? '100%' : undefined,
+						} }
+					>
+						<Tabs.Tab tabId="tab1">
+							Label with multiple words
+						</Tabs.Tab>
+						<Tabs.Tab tabId="tab2">Short</Tabs.Tab>
+						<Tabs.Tab tabId="tab3">
+							Hippopotomonstrosesquippedaliophobia
+						</Tabs.Tab>
+						<Tabs.Tab tabId="tab4">Tab 4</Tabs.Tab>
+						<Tabs.Tab tabId="tab5">Tab 5</Tabs.Tab>
+					</Tabs.TabList>
+				</div>
+				<Tabs.TabPanel tabId="tab1">
+					<p>Selected tab: Tab 1</p>
+					<p>(Label with multiple words)</p>
+				</Tabs.TabPanel>
+				<Tabs.TabPanel tabId="tab2">
+					<p>Selected tab: Tab 2</p>
+					<p>(Short)</p>
+				</Tabs.TabPanel>
+				<Tabs.TabPanel tabId="tab3">
+					<p>Selected tab: Tab 3</p>
+					<p>(Hippopotomonstrosesquippedaliophobia)</p>
+				</Tabs.TabPanel>
+				<Tabs.TabPanel tabId="tab4">
+					<p>Selected tab: Tab 4</p>
+				</Tabs.TabPanel>
+				<Tabs.TabPanel tabId="tab5">
+					<p>Selected tab: Tab 5</p>
+				</Tabs.TabPanel>
+			</Tabs>
+		</div>
+	);
+};
+SizeAndOverflowPlayground.args = {
+	defaultTabId: 'tab4',
+};
+
 const VerticalTemplate: StoryFn< typeof Tabs > = ( props ) => {
 	return (
 		<Tabs orientation="vertical" { ...props }>

packages/components/src/tabs/styles.ts

@@ -16,32 +16,40 @@ export const TabListWrapper = styled.div`
 	align-items: stretch;
 	flex-direction: row;
 	text-align: center;
+	overflow-x: auto;
 
 	&[aria-orientation='vertical'] {
 		flex-direction: column;
 		text-align: start;
 	}
 
-	@media not ( prefers-reduced-motion ) {
-		&.is-animation-enabled::after {
-			transition-property: transform;
-			transition-duration: 0.2s;
-			transition-timing-function: ease-out;
-		}
+	:where( [aria-orientation='horizontal'] ) {
+		width: fit-content;
 	}
+
 	--direction-factor: 1;
-	--direction-origin-x: left;
+	--direction-start: left;
+	--direction-end: right;
 	--indicator-start: var( --indicator-left );
 	&:dir( rtl ) {
 		--direction-factor: -1;
-		--direction-origin-x: right;
+		--direction-start: right;
+		--direction-end: left;
 		--indicator-start: var( --indicator-right );
 	}
-	&::after {
+
+	@media not ( prefers-reduced-motion ) {
+		&.is-animation-enabled::before {
+			transition-property: transform;
+			transition-duration: 0.2s;
+			transition-timing-function: ease-out;
+		}
+	}
+	&::before {
 		content: '';
 		position: absolute;
 		pointer-events: none;
-		transform-origin: var( --direction-origin-x ) top;
+		transform-origin: var( --direction-start ) top;
 
 		// Windows high contrast mode.
 		outline: 2px solid transparent;
@@ -52,7 +60,31 @@ export const TabListWrapper = styled.div`
 			when scaling in the transform, see: https://stackoverflow.com/a/52159123 */
 	--antialiasing-factor: 100;
 	&:not( [aria-orientation='vertical'] ) {
-		&::after {
+		--fade-width: 4rem;
+		--fade-gradient-base: transparent 0%, black var( --fade-width );
+		--fade-gradient-composed: var( --fade-gradient-base ), black 60%,
+			transparent 50%;
+		&.is-overflowing-first {
+			mask-image: linear-gradient(
+				to var( --direction-end ),
+				var( --fade-gradient-base )
+			);
+		}
+		&.is-overflowing-last {
+			mask-image: linear-gradient(
+				to var( --direction-start ),
+				var( --fade-gradient-base )
+			);
+		}
+		&.is-overflowing-first.is-overflowing-last {
+			mask-image: linear-gradient(
+					to right,
+					var( --fade-gradient-composed )
+				),
+				linear-gradient( to left, var( --fade-gradient-composed ) );
+		}
+
+		&::before {
 			bottom: 0;
 			height: 0;
 			width: calc( var( --antialiasing-factor ) * 1px );
@@ -71,8 +103,7 @@ export const TabListWrapper = styled.div`
 				${ COLORS.theme.accent };
 		}
 	}
-	&[aria-orientation='vertical']::after {
-		z-index: -1;
+	&[aria-orientation='vertical']::before {
 		top: 0;
 		left: 0;
 		width: 100%;
@@ -87,14 +118,14 @@ export const TabListWrapper = styled.div`
 
 export const Tab = styled( Ariakit.Tab )`
 	& {
+		scroll-margin: 24px;
+		flex-grow: 1;
+		flex-shrink: 0;
 		display: inline-flex;
 		align-items: center;
 		position: relative;
 		border-radius: 0;
-		min-height: ${ space(
-			12
-		) }; // Avoid fixed height to allow for long strings that go in multiple lines.
-		height: auto;
+		height: ${ space( 12 ) };
 		background: transparent;
 		border: none;
 		box-shadow: none;
@@ -104,7 +135,6 @@ export const Tab = styled( Ariakit.Tab )`
 		margin-left: 0;
 		font-weight: 500;
 		text-align: inherit;
-		hyphens: auto;
 		color: ${ COLORS.theme.foreground };
 
 		&[aria-disabled='true'] {
@@ -123,7 +153,7 @@ export const Tab = styled( Ariakit.Tab )`
 		}
 
 		// Focus.
-		&::before {
+		&::after {
 			content: '';
 			position: absolute;
 			top: ${ space( 3 ) };
@@ -146,7 +176,7 @@ export const Tab = styled( Ariakit.Tab )`
 			}
 		}
 
-		&:focus-visible::before {
+		&:focus-visible::after {
 			opacity: 1;
 		}
 	}
@@ -156,6 +186,10 @@ export const Tab = styled( Ariakit.Tab )`
 			10
 		) }; // Avoid fixed height to allow for long strings that go in multiple lines.
 	}
+
+	[aria-orientation='horizontal'] & {
+		justify-content: center;
+	}
 `;
 
 export const TabPanel = styled( Ariakit.TabPanel )`