fix disabled tab tabbing

docs/resources/changelog.md

@@ -22,6 +22,7 @@ _During the beta period, these restrictions may be relaxed in the event of a mis
 - Fixed a bug in `<sl-color-picker>` that caused the trigger and color preview to ignore opacity on first render [#869](https://github.com/shoelace-style/shoelace/issues/869)
 - Fixed a bug in `<sl-tree>` that prevented the keyboard from working when the component was nested in a shadow root [#871](https://github.com/shoelace-style/shoelace/issues/871)
 - Fixed a bug in `<sl-tab-group>` that prevented the keyboard from working when the component was nested in a shadow root [#872](https://github.com/shoelace-style/shoelace/issues/872)
+- Fixed a bug in `<sl-tab>` that allowed disabled tabs to erroneously receive focus
 - Improved single selection in `<sl-tree>` so nodes expand and collapse and receive selection when clicking on the label
 - Renamed `expanded-icon` and `collapsed-icon` slots to `expand-icon` and `collapse-icon` in the experimental `<sl-tree>` and `<sl-tree-item>` components
 - Improved RTL support for `<sl-image-comparer>`

src/components/tab/tab.ts

@@ -88,7 +88,7 @@ export default class SlTab extends ShoelaceElement {
           'tab--closable': this.closable,
           'tab--disabled': this.disabled
         })}
-        tabindex="0"
+        tabindex=${this.disabled ? '-1' : '0'}
       >
         <slot></slot>
         ${this.closable