@demiankatz, just a quick question—would changing the event from "Hide" to "Show" help trigger the infobox pop-up for testing? Another thing to check would be if there's a manifest that requires authentication. Clicking the "More" button in that scenario should trigger the infobox to appear as well.

I tried something similar to that but had trouble getting it to work. I can probably try again tomorrow when I have a bit more time, though, if nobody can share with us a manifest to trigger the message in the meantime!

I looked again. The problem here is that triggering the SHOW_INFORMATION event requires an IExternalResource object, which is something to do with the authentication system. I'm not sure how to create or simulate one of these outside of the actual authentication workflow.

Ahh, I figured out a way! I created a showFakeInformation() method that's a copy of showInformation() with the auth-specific logic replaced with a hard-coded "hello world" and I wired that method up to get called when I click on the settings button. Here's a patch of my hack:

diff --git a/src/content-handlers/iiif/modules/uv-shared-module/HeaderPanel.ts b/src/content-handlers/iiif/modules/uv-shared-module/HeaderPanel.ts
index bcabeb39..355b7db6 100644
--- a/src/content-handlers/iiif/modules/uv-shared-module/HeaderPanel.ts
+++ b/src/content-handlers/iiif/modules/uv-shared-module/HeaderPanel.ts
@@ -93,6 +93,7 @@ export class HeaderPanel<
     });
 
     this.$settingsButton.onPressed(() => {
+      this.showFakeInformation();
       this.extensionHost.publish(
         IIIFEvents.SHOW_SETTINGS_DIALOGUE,
         this.$settingsButton
@@ -146,6 +147,23 @@ export class HeaderPanel<
     return false;
   }
 
+  showFakeInformation(): void {
+    var $message = this.$informationBox.find(".message");
+    $message
+      .html("hello world")
+      .find("a")
+      .attr("target", "_top");
+    var $actions = this.$informationBox.find(".actions");
+    $actions.empty();
+
+    this.extensionHost.publish(IIIFEvents.MESSAGE_DISPLAYED, this.information);
+
+    this.$informationBox.attr("aria-hidden", "false");
+    this.$informationBox.show();
+    this.$element.addClass("showInformation");
+    this.extension.resize();
+  }
+
   showInformation(args: InformationArgs): void {
     const informationFactory: InformationFactory = new InformationFactory(
       this.extension

With that in place, I was able to confirm that the close button in the info box includes an appropriately translated aria-label, as evidenced by this screen shot showing the Welsh translation:

I think this is the best we are going to be able to do testing-wise without a real demonstration manifest. If that's enough for you to be satisfied, please approve and I'll get this merged!