Bugzilla

All existing and new Firefox Labs experiments will have to be managed via Nimbus after that capability is released in Fx 135. 
Since the 135 release is on Feb 4, we should remove the sidebar and vertical checkboxes in Nightly 137 (starting on Feb 3), but no earlier than Feb 4, 2025. 

Once that is done, I will launch a Nimbus rollout to display the sidebar and vertical tabs checkboxes to Nightly 137+ users.

Starting from Nightly 136, we are introducing the new sidebar and vertical tabs settings in about:preferences#general. 

**Location**: between **Tabs** and **Language and Appearance** sections. 

**Horizontal tabs**

This option is selected by default, unless a profile already has vertical tabs enabled prior to setting being introduced. 

**Default values:** 
- sidebar.revamp = false
- sidebar.verticalTabs = false

**Vertical tabs**

If a user had vertical tabs enabled (sidebar.revamp = true + sidebar.verticalTabs = true) prior to the setting introduced, the radio state should reflect it. 

If vertical tabs radio button is enabled: 

- sidebar.revamp = true
- sidebar.verticalTabs = true
- sidebar.visibility = show
- Show sidebar is pre-checked and disabled. A user will have to switch to Horizontal tabs to change the Show sidebar setting. 


**Show sidebar**

This option is not pre-checked by default:

- sidebar.revamp = false 

If Show sidebar checkbox is enabled:
- sidebar.revamp = true
- sidebar.visibility = show (the launcher is visible until a user clicks the sidebar button to hide it)

The checkbox follows the current behavior of the sidebar.revamp pref: 
- Enables new sidebar
- Adds the sidebar toolbar button into the default location if a user didn’t have the sidebar button.
- Leaves the location of the button intact for users who already have it in the toolbar

### Strings
**Section title:** 
*Browser layout*

**Radio labels:**
*Horizontal tabs*
*Display at top of browser*

**Vertical tabs**
*Display on the side, in the sidebar*

**Checkbox label and description:**
*Show sidebar*
*Quickly access bookmarks, tabs from your phone, AI chatbots, and more without leaving your main view.*

Starting from Nightly 136, we are introducing the new sidebar and vertical tabs settings in about:preferences#general. 

**Location**: between **Tabs** and **Language and Appearance** sections. 

**Horizontal tabs**

This option is selected by default, unless a profile already has vertical tabs enabled prior to setting being introduced. 

**Default values:** 
- sidebar.revamp = false
- sidebar.verticalTabs = false

**Vertical tabs**

If a user had vertical tabs enabled (sidebar.revamp = true + sidebar.verticalTabs = true) prior to the setting introduced, the radio state should reflect it. 

If vertical tabs radio button is enabled: 

- sidebar.revamp = true
- sidebar.verticalTabs = true
- sidebar.visibility = show
- Show sidebar is pre-checked and disabled. A user will have to switch to Horizontal tabs to change the Show sidebar setting. 


**Show sidebar**

This option is not pre-checked by default:

- sidebar.revamp = false 

If Show sidebar checkbox is enabled:
- sidebar.revamp = true
- sidebar.visibility = show (the launcher is visible until a user clicks the sidebar button to hide it)

The checkbox follows the current behavior of the sidebar.revamp pref: 
- Enables new sidebar
- Adds the sidebar toolbar button into the default location if a user didn’t have the sidebar button.
- Leaves the location of the button intact for users who already have it in the toolbar

### Strings
**Section title:** 
*Browser layout*

**Radio labels**
*Horizontal tabs*
*Display at top of browser*

**Vertical tabs**
*Display on the side, in the sidebar*

**Checkbox label and description:**
*Show sidebar*
*Quickly access bookmarks, tabs from your phone, AI chatbots, and more without leaving your main view.*

Starting from Nightly 136, we are introducing the new sidebar and vertical tabs settings in about:preferences#general. 

**Location**: between **Tabs** and **Language and Appearance** sections. 

**Horizontal tabs**
This option is selected by default, unless a profile already has vertical tabs enabled prior to setting being introduced. 

**Default values:** 
- sidebar.revamp = false
- sidebar.verticalTabs = false

**Vertical tabs**

If a user had vertical tabs enabled (sidebar.revamp = true + sidebar.verticalTabs = true) prior to the setting introduced, the radio state should reflect it. If vertical tabs radio button is enabled: 

- sidebar.revamp = true
- sidebar.verticalTabs = true
- sidebar.visibility = show
- Show sidebar is pre-checked and disabled. A user will have to switch to Horizontal tabs to change the Show sidebar setting. 


**Show sidebar**

This option is not pre-checked by default:

- sidebar.revamp = false 

If Show sidebar checkbox is enabled:
- sidebar.revamp = true
- sidebar.visibility = show (the launcher is visible until a user clicks the sidebar button to hide it)

The checkbox follows the current behavior of the sidebar.revamp pref: 
- Enables new sidebar
- Adds the sidebar toolbar button into the default location if a user didn’t have the sidebar button.
- Leaves the location of the button intact for users who already have it in the toolbar

### Strings
**Section title:** 
*Browser layout*

**Radio labels**
*Horizontal tabs*
*Display at top of browser*

**Vertical tabs**
*Display on the side, in the sidebar*

**Checkbox label and description:**
*Show sidebar*
*Quickly access bookmarks, tabs from your phone, AI chatbots, and more without leaving your main view.*

Starting from Nightly 136, we need to:
- remove Sidebar and Vertical tabs checkboxes from Labs. 
-  introduce the new sidebar and vertical tabs settings in about:preferences#general. 

**Location**: between **Tabs** and **Language and Appearance** sections. 

**Horizontal tabs**
This option is selected by default, unless a profile already has vertical tabs enabled prior to setting being introduced. 

**Default values:** 
- sidebar.revamp = false
- sidebar.verticalTabs = false

**Vertical tabs**

If a user had vertical tabs enabled (sidebar.revamp = true + sidebar.verticalTabs = true) prior to the setting introduced, the radio state should reflect it. If vertical tabs radio button is enabled: 

- sidebar.revamp = true
- sidebar.verticalTabs = true
- sidebar.visibility = show
- Show sidebar is pre-checked and disabled. A user will have to switch to Horizontal tabs to change the Show sidebar setting. 


**Show sidebar**

This option is not pre-checked by default:

- sidebar.revamp = false 

If Show sidebar checkbox is enabled:
- sidebar.revamp = true
- sidebar.visibility = show (the launcher is visible until a user clicks the sidebar button to hide it)

The checkbox follows the current behavior of the sidebar.revamp pref: 
- Enables new sidebar
- Adds the sidebar toolbar button into the default location if a user didn’t have the sidebar button.
- Leaves the location of the button intact for users who already have it in the toolbar

### Strings
**Section title:** 
*Browser layout*

**Radio labels**
*Horizontal tabs*
*Display at top of browser*

**Vertical tabs**
*Display on the side, in the sidebar*

**Checkbox label and description:**
*Show sidebar*
*Quickly access bookmarks, tabs from your phone, AI chatbots, and more without leaving your main view.*

Starting from Nightly 136, we need to:
- remove Sidebar and Vertical tabs checkboxes from Labs. 
-  introduce the new **Browser layout** section for sidebar and vertical tabs settings in about:preferences#general. 

**Browser layout section location**: between **Tabs** and **Language and Appearance** sections. 

**Horizontal tabs**
This option is selected by default, unless a profile already has vertical tabs enabled prior to setting being introduced. 

**Default values:** 
- sidebar.revamp = false
- sidebar.verticalTabs = false

**Vertical tabs**

If a user had vertical tabs enabled (sidebar.revamp = true + sidebar.verticalTabs = true) prior to the setting introduced, the radio state should reflect it. If vertical tabs radio button is enabled: 

- sidebar.revamp = true
- sidebar.verticalTabs = true
- sidebar.visibility = show
- Show sidebar is pre-checked and disabled. A user will have to switch to Horizontal tabs to change the Show sidebar setting. 


**Show sidebar**

This option is not pre-checked by default:

- sidebar.revamp = false 

If Show sidebar checkbox is enabled:
- sidebar.revamp = true
- sidebar.visibility = show (the launcher is visible until a user clicks the sidebar button to hide it)

The checkbox follows the current behavior of the sidebar.revamp pref: 
- Enables new sidebar
- Adds the sidebar toolbar button into the default location if a user didn’t have the sidebar button.
- Leaves the location of the button intact for users who already have it in the toolbar

### Strings
**Section title:** 
*Browser layout*

**Radio labels**
*Horizontal tabs*
*Display at top of browser*

**Vertical tabs**
*Display on the side, in the sidebar*

**Checkbox label and description:**
*Show sidebar*
*Quickly access bookmarks, tabs from your phone, AI chatbots, and more without leaving your main view.*