Customize Widgets: Fix block toolbar deselection when clicking scroll…

…bar (#32762)

* Remove overflow inherit style

* Switch to using mousedown instead of focusin

* Revert style change

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

@@ -13,7 +13,6 @@
 	transition: border-color 0.1s linear, box-shadow 0.1s linear;
 	@include reduce-motion("transition");
 
-	// Allow overflow on desktop.
 	@include break-small() {
 		overflow: inherit;
 	}

packages/customize-widgets/src/components/customize-widgets/use-clear-selected-block.js

@@ -52,20 +52,23 @@ export default function useClearSelectedBlock( sidebarControl, popoverRef ) {
 				}
 			}
 
-			// Handle focusing in the same document.
-			function handleFocus( event ) {
+			// Handle mouse down in the same document.
+			function handleMouseDown( event ) {
 				handleClearSelectedBlock( event.target );
 			}
 			// Handle focusing outside the current document, like to iframes.
 			function handleBlur() {
 				handleClearSelectedBlock( ownerDocument.activeElement );
 			}
 
-			ownerDocument.addEventListener( 'focusin', handleFocus );
+			ownerDocument.addEventListener( 'mousedown', handleMouseDown );
 			ownerWindow.addEventListener( 'blur', handleBlur );
 
 			return () => {
-				ownerDocument.removeEventListener( 'focusin', handleFocus );
+				ownerDocument.removeEventListener(
+					'mousedown',
+					handleMouseDown
+				);
 				ownerWindow.removeEventListener( 'blur', handleBlur );
 			};
 		}