diff --git a/browser/components/tabbrowser/content/tabbrowser.js b/browser/components/tabbrowser/content/tabbrowser.js
index 9fbb3d93746d..6104bdad5fb1 100644
--- a/browser/components/tabbrowser/content/tabbrowser.js
+++ b/browser/components/tabbrowser/content/tabbrowser.js
@@ -11377,6 +11377,9 @@ addTabGroup
 (
 tabs
 {
+id
+=
+null
 color
 =
 null
@@ -11433,7 +11436,12 @@ tabGroupMenu
 nextUnusedColor
 ;
 }
-let
+if
+(
+!
+id
+)
+{
 id
 =
 {
@@ -11459,6 +11467,7 @@ random
 )
 }
 ;
+}
 let
 group
 =
@@ -20667,6 +20676,154 @@ return
 win
 ;
 }
+replaceGroupWithWindow
+(
+group
+)
+{
+let
+selectedIndex
+=
+group
+.
+tabs
+.
+indexOf
+(
+gBrowser
+.
+selectedTab
+)
+;
+if
+(
+selectedIndex
+<
+0
+)
+{
+selectedIndex
+=
+0
+;
+}
+let
+firstTab
+=
+group
+.
+tabs
+[
+selectedIndex
+]
+;
+let
+newWindow
+=
+this
+.
+replaceTabWithWindow
+(
+firstTab
+)
+;
+newWindow
+.
+addEventListener
+(
+"
+before
+-
+initial
+-
+tab
+-
+adopted
+"
+(
+)
+=
+>
+{
+let
+tabsToGroup
+=
+group
+.
+tabs
+.
+map
+(
+(
+tab
+i
+)
+=
+>
+{
+if
+(
+i
+=
+=
+selectedIndex
+)
+{
+return
+newWindow
+.
+gBrowser
+.
+visibleTabs
+[
+0
+]
+;
+}
+return
+tab
+;
+}
+)
+;
+newWindow
+.
+gBrowser
+.
+addTabGroup
+(
+tabsToGroup
+{
+color
+:
+group
+.
+color
+label
+:
+group
+.
+label
+id
+:
+group
+.
+id
+}
+)
+;
+}
+{
+once
+:
+true
+}
+)
+;
+return
+newWindow
+;
+}
 _updateTabsAfterInsert
 (
 )
diff --git a/browser/components/tabbrowser/content/tabgroup-menu.js b/browser/components/tabbrowser/content/tabgroup-menu.js
index 646a83993ee7..4099ef520f9f 100644
--- a/browser/components/tabbrowser/content/tabgroup-menu.js
+++ b/browser/components/tabbrowser/content/tabgroup-menu.js
@@ -501,6 +501,11 @@ only
 >
 <
 toolbarbutton
+tabindex
+=
+"
+1
+"
 id
 =
 "
@@ -537,10 +542,10 @@ toolbarbutton
 >
 <
 toolbarbutton
-disabled
+tabindex
 =
 "
-true
+1
 "
 id
 =
@@ -617,6 +622,11 @@ toolbarbutton
 >
 <
 toolbarbutton
+tabindex
+=
+"
+1
+"
 id
 =
 "
@@ -1057,6 +1067,37 @@ document
 getElementById
 (
 "
+tabGroupEditor_moveGroupToNewWindow
+"
+)
+.
+addEventListener
+(
+"
+command
+"
+(
+)
+=
+>
+{
+gBrowser
+.
+replaceGroupWithWindow
+(
+this
+.
+activeGroup
+)
+;
+}
+)
+;
+document
+.
+getElementById
+(
+"
 tabGroupEditor_ungroupTabs
 "
 )
@@ -1686,6 +1727,31 @@ topleft
 }
 )
 ;
+document
+.
+getElementById
+(
+"
+tabGroupEditor_moveGroupToNewWindow
+"
+)
+.
+disabled
+=
+gBrowser
+.
+openTabCount
+=
+=
+this
+.
+activeGroup
+?
+.
+tabs
+.
+length
+;
 }
 on_popupshown
 (
diff --git a/browser/components/tabbrowser/content/tabgroup.js b/browser/components/tabbrowser/content/tabgroup.js
index 2f43139a3d6d..e4b98b7ae388 100644
--- a/browser/components/tabbrowser/content/tabgroup.js
+++ b/browser/components/tabbrowser/content/tabgroup.js
@@ -741,7 +741,7 @@ gBrowser
 adoptTab
 (
 tab
-this
+gBrowser
 .
 tabs
 .
@@ -754,6 +754,9 @@ at
 _tPos
 +
 1
+tab
+.
+selected
 )
 ;
 gBrowser
diff --git a/browser/components/tabbrowser/test/browser/tabs/browser_tab_groups.js b/browser/components/tabbrowser/test/browser/tabs/browser_tab_groups.js
index d3aef168323b..671744416046 100644
--- a/browser/components/tabbrowser/test/browser/tabs/browser_tab_groups.js
+++ b/browser/components/tabbrowser/test/browser/tabs/browser_tab_groups.js
@@ -6790,6 +6790,10 @@ async
 function
 createTabGroupAndOpenEditPanel
 (
+tabs
+=
+[
+]
 )
 {
 let
@@ -6815,6 +6819,14 @@ tabgroupEditor
 .
 panel
 ;
+if
+(
+!
+tabs
+.
+length
+)
+{
 let
 tab
 =
@@ -6835,6 +6847,13 @@ false
 }
 )
 ;
+tabs
+=
+[
+tab
+]
+;
+}
 let
 panelShown
 =
@@ -6855,9 +6874,7 @@ gBrowser
 .
 addTabGroup
 (
-[
-tab
-]
+tabs
 {
 color
 :
@@ -6976,8 +6993,6 @@ resolve
 (
 {
 tabgroupEditor
-tabgroupPanel
-tab
 group
 }
 )
@@ -6999,7 +7014,7 @@ test_tabGroupPanelAddTab
 {
 let
 {
-tabgroupPanel
+tabgroupEditor
 group
 }
 =
@@ -7009,6 +7024,13 @@ createTabGroupAndOpenEditPanel
 )
 ;
 let
+tabgroupPanel
+=
+tabgroupEditor
+.
+panel
+;
+let
 addNewTabButton
 =
 tabgroupPanel
@@ -7131,8 +7153,7 @@ test_tabGroupPanelUngroupTabs
 {
 let
 {
-tabgroupPanel
-tab
+tabgroupEditor
 group
 }
 =
@@ -7142,6 +7163,23 @@ createTabGroupAndOpenEditPanel
 )
 ;
 let
+tabgroupPanel
+=
+tabgroupEditor
+.
+panel
+;
+let
+tab
+=
+group
+.
+tabs
+[
+0
+]
+;
+let
 ungroupTabsButton
 =
 tabgroupPanel
@@ -7225,3 +7263,479 @@ tab
 }
 )
 ;
+add_task
+(
+async
+function
+test_moveGroupToNewWindow
+(
+)
+{
+let
+tabs
+=
+[
+BrowserTestUtils
+.
+addTab
+(
+gBrowser
+"
+about
+:
+cache
+"
+{
+skipAnimation
+:
+true
+}
+)
+BrowserTestUtils
+.
+addTab
+(
+gBrowser
+"
+about
+:
+robots
+"
+{
+skipAnimation
+:
+true
+}
+)
+BrowserTestUtils
+.
+addTab
+(
+gBrowser
+"
+about
+:
+mozilla
+"
+{
+skipAnimation
+:
+true
+}
+)
+]
+;
+gBrowser
+.
+selectedTab
+=
+tabs
+[
+1
+]
+;
+let
+assertTabsInCorrectOrder
+=
+tabsToCheck
+=
+>
+{
+Assert
+.
+equal
+(
+tabsToCheck
+[
+0
+]
+.
+linkedBrowser
+.
+currentURI
+.
+spec
+"
+about
+:
+cache
+"
+"
+about
+:
+cache
+is
+first
+"
+)
+;
+Assert
+.
+equal
+(
+tabsToCheck
+[
+1
+]
+.
+linkedBrowser
+.
+currentURI
+.
+spec
+"
+about
+:
+robots
+"
+"
+about
+:
+robots
+is
+second
+"
+)
+;
+Assert
+.
+equal
+(
+tabsToCheck
+[
+2
+]
+.
+linkedBrowser
+.
+currentURI
+.
+spec
+"
+about
+:
+mozilla
+"
+"
+about
+:
+mozilla
+is
+third
+"
+)
+;
+}
+;
+let
+{
+group
+}
+=
+await
+createTabGroupAndOpenEditPanel
+(
+tabs
+)
+;
+let
+newWindowOpened
+=
+BrowserTestUtils
+.
+waitForNewWindow
+(
+)
+;
+document
+.
+getElementById
+(
+"
+tabGroupEditor_moveGroupToNewWindow
+"
+)
+.
+click
+(
+)
+;
+let
+newWin
+=
+await
+newWindowOpened
+;
+Assert
+.
+ok
+(
+newWin
+!
+=
+window
+"
+Group
+is
+moved
+to
+new
+window
+"
+)
+;
+let
+movedTabs
+=
+newWin
+.
+gBrowser
+.
+tabs
+;
+let
+movedGroup
+=
+movedTabs
+[
+0
+]
+.
+group
+;
+Assert
+.
+equal
+(
+movedGroup
+.
+id
+group
+.
+id
+"
+Tab
+is
+in
+original
+group
+"
+)
+;
+Assert
+.
+equal
+(
+newWin
+.
+gBrowser
+.
+selectedTab
+newWin
+.
+gBrowser
+.
+tabs
+[
+1
+]
+"
+Second
+tab
+remains
+selected
+"
+)
+;
+assertTabsInCorrectOrder
+(
+newWin
+.
+gBrowser
+.
+tabs
+)
+;
+let
+tabgroupEditor
+=
+newWin
+.
+document
+.
+getElementById
+(
+"
+tab
+-
+group
+-
+editor
+"
+)
+;
+let
+panelOpen
+=
+BrowserTestUtils
+.
+waitForPopupEvent
+(
+tabgroupEditor
+.
+panel
+"
+shown
+"
+)
+;
+tabgroupEditor
+.
+openEditModal
+(
+movedGroup
+)
+;
+await
+panelOpen
+;
+let
+moveGroupButton
+=
+newWin
+.
+document
+.
+getElementById
+(
+"
+tabGroupEditor_moveGroupToNewWindow
+"
+)
+;
+Assert
+.
+ok
+(
+moveGroupButton
+.
+disabled
+"
+Button
+is
+disabled
+when
+group
+is
+only
+thing
+in
+window
+"
+)
+;
+let
+panelHidden
+=
+BrowserTestUtils
+.
+waitForPopupEvent
+(
+tabgroupEditor
+.
+panel
+"
+hidden
+"
+)
+;
+tabgroupEditor
+.
+panel
+.
+hidePopup
+(
+)
+;
+await
+panelHidden
+;
+BrowserTestUtils
+.
+addTab
+(
+newWin
+.
+gBrowser
+"
+about
+:
+blank
+"
+{
+skipAnimation
+:
+true
+}
+)
+;
+panelOpen
+=
+BrowserTestUtils
+.
+waitForPopupEvent
+(
+tabgroupEditor
+.
+panel
+"
+shown
+"
+)
+;
+tabgroupEditor
+.
+openEditModal
+(
+movedGroup
+)
+;
+await
+panelOpen
+;
+Assert
+.
+ok
+(
+!
+moveGroupButton
+.
+disabled
+"
+Button
+is
+enabled
+again
+when
+additional
+tab
+present
+"
+)
+;
+await
+BrowserTestUtils
+.
+closeWindow
+(
+newWin
+{
+animate
+:
+false
+}
+)
+;
+}
+)
+;