Fixed misleading announcement for all demos (#823)

diff --git a/lib/l10n/intl_en.arb b/lib/l10n/intl_en.arb
index c7228f9..ed86c68 100644
--- a/lib/l10n/intl_en.arb
+++ b/lib/l10n/intl_en.arb
@@ -2230,6 +2230,10 @@
   "@chipBiking": {
     "description": "A chip component to that indicates a biking selection."
   },
+  "demo": "Demo",
+  "@demo": {
+    "description": "Used in the title of the demos."
+  },
   "dialogDiscardTitle": "Discard draft?",
   "@dialogDiscardTitle": {
     "description": "Alert dialog message to discard draft."
diff --git a/lib/l10n/intl_en_US.xml b/lib/l10n/intl_en_US.xml
index 20078c0..dd9d120 100644
--- a/lib/l10n/intl_en_US.xml
+++ b/lib/l10n/intl_en_US.xml
@@ -2098,6 +2098,10 @@
     description="A chip component to that indicates a biking selection."
     >Biking</string>
   <string
+    name="demo"
+    description="Used in the title of the demos."
+    >Demo</string>
+  <string
     name="dialogDiscardTitle"
     description="Alert dialog message to discard draft."
     >Discard draft?</string>
diff --git a/lib/pages/demo.dart b/lib/pages/demo.dart
index aff7dd4..2e6be0b 100644
--- a/lib/pages/demo.dart
+++ b/lib/pages/demo.dart
@@ -428,17 +428,18 @@
       final isDemoNormal = currentDemoState == _DemoState.normal;
       // Add a tap gesture to collapse the currently opened section.
       demoContent = Semantics(
-        label: MaterialLocalizations.of(context).modalBarrierDismissLabel,
+        label:
+            '${GalleryLocalizations.of(context)!.demo}, ${widget.demo.title}',
         child: MouseRegion(
           cursor: isDemoNormal ? MouseCursor.defer : SystemMouseCursors.click,
           child: GestureDetector(
-            onTap: () {
-              if (!isDemoNormal) {
-                setStateAndUpdate(() {
-                  _demoStateIndex.value = _DemoState.normal.index;
-                });
-              }
-            },
+            onTap: isDemoNormal
+                ? null
+                : () {
+                    setStateAndUpdate(() {
+                      _demoStateIndex.value = _DemoState.normal.index;
+                    });
+                  },
             child: Semantics(
               excludeSemantics: !isDemoNormal,
               child: demoContent,