fix: Fix keyboard navigation for the continuous toolbox

Author: gonfunko

plugins/continuous-toolbox/src/ContinuousFlyout.ts

@@ -192,6 +192,23 @@ export class ContinuousFlyout extends Blockly.VerticalFlyout {
     this.scrollTo(position);
   }
 
+  /**
+   * Returns the header item in the flyout corresponding to the given
+   * toolbox category, if any.
+   */
+  headerForCategory(
+    category: Blockly.ISelectableToolboxItem,
+  ): Blockly.IFocusableNode | undefined {
+    return this.getContents()
+      .find((item) => {
+        return (
+          this.toolboxItemIsLabel(item) &&
+          item.getElement().getButtonText() === category.getName()
+        );
+      })
+      ?.getElement();
+  }
+
   /**
    * Step the scrolling animation by scrolling a fraction of the way to
    * a scroll target, and request the next frame if necessary.

plugins/continuous-toolbox/src/ContinuousToolbox.ts

@@ -10,6 +10,7 @@
 
 import * as Blockly from 'blockly/core';
 import {ContinuousFlyout} from './ContinuousFlyout';
+import {ContinuousToolboxNavigator} from './ContinuousToolboxNavigator';
 
 /**
  * Class for continuous toolbox.
@@ -21,6 +22,12 @@ export class ContinuousToolbox extends Blockly.Toolbox {
    */
   private refreshDebouncer?: ReturnType<typeof setTimeout>;
 
+  /**
+   * Navigator object responsible for handling keyboard navigation within this
+   * toolbox.
+   */
+  private continuousToolboxNavigator = new ContinuousToolboxNavigator(this);
+
   /**
    * Initializes the continuous toolbox.
    */
@@ -192,4 +199,12 @@ export class ContinuousToolbox extends Blockly.Toolbox {
     }
     return super.getClientRect();
   }
+
+  /**
+   * Returns the Navigator object responsible for handling keyboard navigation
+   * inside this toolbox.
+   */
+  override getNavigator(): Blockly.ToolboxNavigator {
+    return this.continuousToolboxNavigator;
+  }
 }

plugins/continuous-toolbox/src/ContinuousToolboxNavigator.ts

@@ -0,0 +1,29 @@
+/**
+ * @license
+ * Copyright 2026 Raspberry Pi Foundation
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import * as Blockly from 'blockly/core';
+import {ContinuousToolbox} from './ContinuousToolbox';
+import {ContinuousCategory} from './ContinuousCategory';
+
+/**
+ * A Navigator that handles keyboard navigation within a continuous toolbox.
+ */
+export class ContinuousToolboxNavigator extends Blockly.ToolboxNavigator {
+  constructor(protected toolbox: ContinuousToolbox) {
+    super(toolbox);
+  }
+
+  /**
+   * Returns the next node when navigating "in", in this case the first flyout
+   * item in the toolbox's currently selected category.
+   */
+  override getInNode(
+    node = Blockly.getFocusManager().getFocusedNode(),
+  ): Blockly.IFocusableNode | null {
+    if (!(node instanceof ContinuousCategory)) return null;
+    return this.toolbox.getFlyout().headerForCategory(node) ?? null;
+  }
+}