docs: URL params guide for NTP

special-pages/pages/new-tab/app/new-tab.md

@@ -1,6 +1,6 @@
 ---
 title: New Tab Page
-children: 
+children:
   - ./widget-list/widget-config.md
   - ./remote-messaging-framework/rmf.md
   - ./update-notification/update-notification.md
@@ -26,7 +26,7 @@ children:
 
 ## Notifications
 
-### `contextMenu` 
+### `contextMenu`
 - {@link "NewTab Messages".ContextMenuNotification}
 - Sent when the user right-clicks in the page
 - Note: Other widgets might prevent this (and send their own, eg: favorites)
@@ -84,3 +84,168 @@ children:
 - {@link "NewTab Messages".ReportPageExceptionNotification}
 - Sent when the application failed after initialization (for example, a JavaScript exception prevented it)
 - Sends: `{ message: string }` - see {@link "NewTab Messages".ReportPageExceptionNotify}
+
+# URL Search Parameter Reference Guide
+
+This comprehensive guide documents all available URL search parameters for testing, reviews, and development purposes. Use these parameters to trigger specific states, features, or experiments without modifying code.
+
+## Page-Level Parameters
+
+### Component Display View
+- **Purpose**: Displays configurable stickersheet view outside normal page flow
+- **Parameter**: `display`
+- **Example**: `?display=components`
+- **Options**:
+  - `components` - Shows component stickersheet
+
+### Language/Locale Selector
+- **Purpose**: Tests UI with different languages to verify layout and translations
+- **Parameter**: `locale`
+- **Example**: `?locale=fr`
+- **Options**: Any language code available in the [locale directory](../public/locales)
+
+### Text Length Modifier
+- **Purpose**: Tests UI with different text lengths to verify layout flexibility
+- **Parameter**: `textLength`
+- **Example**: `?textLength=1.5`
+- **Options**:
+  - Number higher than 1
+
+### Platform Simulator
+- **Purpose**: Simulates different platforms for testing
+- **Parameter**: `platform`
+- **Example**: `?platform=windows`
+- **Options**:
+  - `windows`
+  - `macos`
+  - `android`
+  - `ios`
+  - `integration`
+
+### Animation Toggle
+- **Purpose**: Enables/disables animations for testing
+- **Parameter**: `animation`
+- **Example**: `?animation=none`
+- **Options**:
+  - `view-transitions` - Enables animations
+  - `none` - Disables animations
+
+### Error Testing
+- **Purpose**: Forces error state for testing error handling
+- **Parameter**: `willThrow`
+- **Example**: `?willThrow=true`
+- **Options**:
+  - `true` - Forces an error
+
+## Feature Parameters
+
+### Feed Controls
+- **Purpose**: Modifies feed display and behavior
+- **Parameter**: `feed`
+- **Example**: `?feed=activity`
+- **Options**:
+  - `stats` - Displays the Privacy Stats widget
+  - `activity` - Displays the Activity widget
+  - `both` - Display both privacy widgets
+
+### Favorites
+- **Purpose**: Controls favorites feature (not fully implemented)
+- **Parameter**: `favorites`
+- **Example**: `?favorites=show`
+- **Options**:
+  - `many`
+  - `single`
+  - `none`
+  - `small-icon`
+  - `fallbacks`
+  - `titles`
+
+
+### Stats Display
+- **Purpose**: Controls statistics display
+- **Parameter**: `stats`
+- **Example**: `?stats=show`
+- **Options**:
+  - `show` - Shows statistics
+  - `hide` - Hides statistics
+
+### Stats Update Count
+- **Purpose**: Sets the number of updates for statistics
+- **Parameter**: `stats-update-count`
+- **Example**: `?stats-update-count=5`
+- **Options**: Any positive integer
+
+### Update Notification
+- **Purpose**: Controls update notification display
+- **Parameter**: `update-notification`
+- **Example**: `?update-notification=show`
+- **Options**:
+  - `show` - Shows update notification
+  - `hide` - Hides update notification
+
+### Update Notification Delay
+- **Purpose**: Sets delay before showing update notification
+- **Parameter**: `update-notification-delay`
+- **Example**: `?update-notification-delay=5000`
+- **Options**: Time in milliseconds
+
+### Customizer Auto-Open
+- **Purpose**: Controls whether customizer opens automatically
+- **Parameter**: `customizer_autoOpen`
+- **Example**: `?customizer_autoOpen=true`
+- **Options**:
+  - `true` - Opens customizer automatically
+  - `false` - Does not open customizer automatically
+
+### RMF (Remote Messaging Framework)
+- **Purpose**: Controls Remote Messaging Framework dialog
+- **Parameter**: `rmf`
+- **Example**: `?rmf=show`
+- **Options**:
+  - `show` - Shows RMF dialog
+  - `hide` - Hides RMF dialog
+
+### RMF Delay
+- **Purpose**: Sets delay before showing RMF dialog
+- **Parameter**: `rmf-delay`
+- **Example**: `?rmf-delay=10000`
+- **Options**: Time in milliseconds
+
+## Experiment Parameters
+
+### Freemium PIR Banner
+- **Purpose**: Tests different PIR banner states
+- **Parameter**: `pir`
+- **Example**: `?pir=onboarding`
+- **Options**:
+  - `onboarding` - Shows onboarding PIR banner
+  - `scan_results` - Shows scan results PIR banner
+
+
+
+## Combining Parameters
+
+Parameters can be combined using the `&` character to test multiple features simultaneously:
+
+`
+?display=components&locale=fr&textLength=long
+`
+
+This example shows the component stickersheet in French with long text strings.
+
+## Usage Examples
+
+### For Developers
+- Testing language support: `?locale=de`
+- Testing responsive layouts: `?textLength=long&platform=mobile`
+- Testing error states: `?willThrow=true`
+
+### For Product Reviews
+- Testing experiment variations: `?pir=onboarding`
+- Testing feature states: `?stats=show&feed=empty`
+
+### For Design Reviews
+- Component review: `?display=components`
+- Testing text overflow: `?textLength=long`
+- Testing animations: `?animation=on`
+