diff --git a/indra/llui/llbutton.cpp b/indra/llui/llbutton.cpp
index d07a0dc159..6f149234e4 100644
--- a/indra/llui/llbutton.cpp
+++ b/indra/llui/llbutton.cpp
@@ -97,6 +97,7 @@ LLButton::Params::Params()
     image_overlay_disabled_color("image_overlay_disabled_color", LLColor4::white % 0.3f),
     image_overlay_selected_color("image_overlay_selected_color", LLColor4::white),
     flash_color("flash_color"),
+    flash_alt_color("flash_alt_color"), // <FS:Ansariel> [FS communication UI]
     pad_right("pad_right", LLBUTTON_H_PAD),
     pad_left("pad_left", LLBUTTON_H_PAD),
     pad_bottom("pad_bottom"),
@@ -134,6 +135,7 @@ LLButton::LLButton(const LLButton::Params& p)
     mMouseDownFrame(0),
     mMouseHeldDownCount(0),
     mFlashing( false ),
+    mIsAltFlashColor(false), // <FS:Ansariel> [FS communication UI]
     mCurGlowStrength(0.f),
     mNeedsHighlight(false),
     mUnselectedLabel(p.label()),
@@ -156,6 +158,7 @@ LLButton::LLButton(const LLButton::Params& p)
     mDisabledSelectedLabelColor(p.label_color_disabled_selected()),
     mImageColor(p.image_color()),
     mFlashBgColor(p.flash_color()),
+    mFlashAltBgColor(p.flash_alt_color()), // <FS:Ansariel> [FS communication UI]
     mDisabledImageColor(p.image_color_disabled()),
     mImageOverlay(p.image_overlay()),
     mImageOverlayColor(p.image_overlay_color()),
@@ -840,7 +843,10 @@ void LLButton::draw()
         // provide fade-in and fade-out via flash_color
         if (mFlashingTimer)
         {
-            LLColor4 flash_color = mFlashBgColor.get();
+            // <FS:Ansariel> [FS communication UI]
+            //LLColor4 flash_color = mFlashBgColor.get();
+            LLColor4 flash_color = mIsAltFlashColor ? mFlashAltBgColor.get() : mFlashBgColor.get();
+            // </FS:Ansariel> [FS communication UI]
             use_glow_effect = true;
             glow_type = LLRender::BT_ALPHA; // blend the glow
 
@@ -1118,7 +1124,10 @@ void LLButton::setToggleState(bool b)
     }
 }
 
-void LLButton::setFlashing(bool b, bool force_flashing/* = false */)
+// <FS:Ansariel> [FS communication UI]
+//void LLButton::setFlashing(bool b, bool force_flashing/* = false */)
+void LLButton::setFlashing(bool b, bool force_flashing/* = false */, bool alternate_color/*= false */)
+// </FS:Ansariel> [FS communication UI]
 {
     mForceFlashing = force_flashing;
     if (mFlashingTimer)
@@ -1131,6 +1140,9 @@ void LLButton::setFlashing(bool b, bool force_flashing/* = false */)
         mFlashing = b;
         mFrameTimer.reset();
     }
+
+    // <FS:Ansariel> [FS communication UI]
+    mIsAltFlashColor = alternate_color;
 }
 
 bool LLButton::toggleState()
diff --git a/indra/llui/llbutton.h b/indra/llui/llbutton.h
index 43a7cd6b3b..ad6d911a67 100644
--- a/indra/llui/llbutton.h
+++ b/indra/llui/llbutton.h
@@ -100,7 +100,9 @@ public:
                                 image_overlay_color,
                                 image_overlay_selected_color,
                                 image_overlay_disabled_color,
-                                flash_color;
+                                flash_color,
+                                flash_alt_color; // <FS:Ansariel> [FS communication UI]
+
 
         // layout
         Optional<S32>           pad_right;
@@ -217,7 +219,10 @@ public:
     void            setToggleState(bool b);
 
     void            setHighlight(bool b);
-    void            setFlashing( bool b, bool force_flashing = false );
+    // <FS:Ansariel> [FS communication UI]
+    //void            setFlashing( bool b, bool force_flashing = false );
+    void            setFlashing(bool b, bool force_flashing = false, bool alternate_color = false);
+    // </FS:Ansariel> [FS communication UI]
     bool            getFlashing() const     { return mFlashing; }
     LLFlashTimer*   getFlashTimer() {return mFlashingTimer;}
     void            setFlashColor(const LLUIColor &color) { mFlashBgColor = color; };
@@ -361,6 +366,8 @@ protected:
     LLPointer<LLUIImage>        mImageFlash;
 
     LLUIColor                   mFlashBgColor;
+    // <FS:Ansariel> [FS communication UI]
+    LLUIColor                   mFlashAltBgColor;
 
     LLUIColor                   mImageColor;
     LLUIColor                   mDisabledImageColor;
@@ -373,6 +380,8 @@ protected:
     bool                        mUseEllipses;
     bool                        mUseFontColor;
     bool                        mFlashing;
+    // <FS:Ansariel> [FS communication UI]
+    bool                        mIsAltFlashColor;
 
     LLFontGL::HAlign            mHAlign;
     S32                         mLeftHPad;
diff --git a/indra/llui/llmultifloater.cpp b/indra/llui/llmultifloater.cpp
index 355e5ad13b..e668939263 100644
--- a/indra/llui/llmultifloater.cpp
+++ b/indra/llui/llmultifloater.cpp
@@ -461,10 +461,16 @@ bool LLMultiFloater::isFloaterFlashing(LLFloater* floaterp)
 
     Requires: floaterp != NULL
 **/
-void LLMultiFloater::setFloaterFlashing(LLFloater* floaterp, bool flashing)
+// <FS:Ansariel> [FS communication UI]
+//void LLMultiFloater::setFloaterFlashing(LLFloater* floaterp, bool flashing)
+void LLMultiFloater::setFloaterFlashing(LLFloater* floaterp, bool flashing, bool alternate_color)
+// </FS:Ansariel> [FS communication UI]
 {
     if ( floaterp && floaterp->getHost() == this )
-        mTabContainer->setTabPanelFlashing(floaterp, flashing);
+        // <FS:Ansariel> [FS communication UI]
+        //mTabContainer->setTabPanelFlashing(floaterp, flashing);
+        mTabContainer->setTabPanelFlashing(floaterp, flashing, alternate_color);
+        // </FS:Ansariel> [FS communication UI]
 }
 
 void LLMultiFloater::onTabSelected()
diff --git a/indra/llui/llmultifloater.h b/indra/llui/llmultifloater.h
index 95e3b2d788..75f92a33cd 100644
--- a/indra/llui/llmultifloater.h
+++ b/indra/llui/llmultifloater.h
@@ -68,7 +68,10 @@ public:
     virtual bool        isFloaterFlashing(LLFloater* floaterp);
     virtual S32         getFloaterCount() const;
 
-    virtual void setFloaterFlashing(LLFloater* floaterp, bool flashing);
+    // <FS:Ansariel> [FS communication UI]
+    //virtual void setFloaterFlashing(LLFloater* floaterp, bool flashing);
+    virtual void setFloaterFlashing(LLFloater* floaterp, bool flashing, bool alternate_color = false);
+    // </FS:Ansariel> [FS communication UI]
     virtual bool closeAllFloaters();    //Returns false if the floater could not be closed due to pending confirmation dialogs
     // <FS> Update torn off status and add title bar
     //void setTabContainer(LLTabContainer* tab_container) { if (!mTabContainer) mTabContainer = tab_container; } // LL Code
diff --git a/indra/llui/lltabcontainer.cpp b/indra/llui/lltabcontainer.cpp
index a800c9891f..8c9888c029 100644
--- a/indra/llui/lltabcontainer.cpp
+++ b/indra/llui/lltabcontainer.cpp
@@ -1806,12 +1806,18 @@ bool LLTabContainer::getTabPanelFlashing(LLPanel *child)
     return false;
 }
 
-void LLTabContainer::setTabPanelFlashing(LLPanel* child, bool state )
+// <FS:Ansariel> [FS communication UI]
+//void LLTabContainer::setTabPanelFlashing(LLPanel* child, bool state )
+void LLTabContainer::setTabPanelFlashing(LLPanel* child, bool state, bool alternate_color)
+// </FS:Ansariel> [FS communication UI]
 {
     LLTabTuple* tuple = getTabByPanel(child);
     if( tuple )
     {
-        tuple->mButton->setFlashing( state );
+        // <FS:Ansariel> [FS communication UI]
+        //tuple->mButton->setFlashing( state );
+        tuple->mButton->setFlashing(state, false, alternate_color);
+        // </FS:Ansariel> [FS communication UI]
     }
 }
 
diff --git a/indra/llui/lltabcontainer.h b/indra/llui/lltabcontainer.h
index 243687623d..937e939eb6 100644
--- a/indra/llui/lltabcontainer.h
+++ b/indra/llui/lltabcontainer.h
@@ -222,7 +222,10 @@ public:
     void        setCurrentPanelIndex(S32 index) { mCurrentTabIdx = index; }
 
     bool        getTabPanelFlashing(LLPanel* child);
-    void        setTabPanelFlashing(LLPanel* child, bool state);
+    // <FS:Ansariel> [FS communication UI]
+    //void        setTabPanelFlashing(LLPanel* child, bool state);
+    void        setTabPanelFlashing(LLPanel* child, bool state, bool alternate_color = false);
+    // </FS:Ansariel> [FS communication UI]
     void        setTabImage(LLPanel* child, std::string img_name, const LLColor4& color = LLColor4::white);
     void        setTabImage(LLPanel* child, const LLUUID& img_id, const LLColor4& color = LLColor4::white);
     void        setTabImage(LLPanel* child, LLIconCtrl* icon);
diff --git a/indra/newview/fsfloaterimcontainer.cpp b/indra/newview/fsfloaterimcontainer.cpp
index 1fc05de338..a4db0dc21a 100644
--- a/indra/newview/fsfloaterimcontainer.cpp
+++ b/indra/newview/fsfloaterimcontainer.cpp
@@ -39,6 +39,7 @@
 #include "llchicletbar.h"
 #include "llemojihelper.h"
 #include "lltoolbarview.h"
+#include "llurlregistry.h"
 #include "llvoiceclient.h"
 
 constexpr F32 VOICE_STATUS_UPDATE_INTERVAL = 1.0f;
@@ -316,6 +317,9 @@ void FSFloaterIMContainer::removeFloater(LLFloater* floaterp)
         gSavedSettings.setBOOL(setting_name, true);
         floaterp->setCanClose(true);
     }
+
+    mFlashingTabStates.erase(floaterp);
+
     LLMultiFloater::removeFloater(floaterp);
 }
 // [/SL:KB]
@@ -345,21 +349,17 @@ void FSFloaterIMContainer::onCloseFloater(LLUUID& id)
     }
 }
 
-void FSFloaterIMContainer::onNewMessageReceived(const LLSD& data)
+void FSFloaterIMContainer::onNewMessageReceived(const LLSD& msg)
 {
-    LLUUID session_id = data["session_id"].asUUID();
+    LLUUID session_id = msg["session_id"].asUUID();
     LLFloater* floaterp = get_ptr_in_map(mSessions, session_id);
     LLFloater* current_floater = LLMultiFloater::getActiveFloater();
 
     // KC: Don't flash tab on friend status changes per setting
     if (floaterp && current_floater && floaterp != current_floater
-        && (gSavedSettings.getBOOL("FSIMChatFlashOnFriendStatusChange") || !data.has("from_id") || data["from_id"].asUUID().notNull()))
+        && (gSavedSettings.getBOOL("FSIMChatFlashOnFriendStatusChange") || !msg.has("from_id") || msg["from_id"].asUUID().notNull()))
     {
-        if (LLMultiFloater::isFloaterFlashing(floaterp))
-        {
-            LLMultiFloater::setFloaterFlashing(floaterp, false);
-        }
-        LLMultiFloater::setFloaterFlashing(floaterp, true);
+        startFlashingTab(floaterp, msg["message"].asString());
     }
 }
 
@@ -559,16 +559,15 @@ void FSFloaterIMContainer::addFlashingSession(const LLUUID& session_id)
     uuid_vec_t::iterator found = std::find(mFlashingSessions.begin(), mFlashingSessions.end(), session_id);
     if (found == mFlashingSessions.end())
     {
-        mFlashingSessions.push_back(session_id);
+        mFlashingSessions.emplace_back(session_id);
     }
+
+    checkFlashing();
 }
 
 void FSFloaterIMContainer::checkFlashing()
 {
-    if (mFlashingSessions.empty())
-    {
-        gToolBarView->flashCommand(LLCommandId("chat"), false);
-    }
+    gToolBarView->flashCommand(LLCommandId("chat"), !mFlashingSessions.empty(), isMinimized());
 }
 
 void FSFloaterIMContainer::sessionIDUpdated(const LLUUID& old_session_id, const LLUUID& new_session_id)
@@ -584,5 +583,21 @@ void FSFloaterIMContainer::sessionIDUpdated(const LLUUID& old_session_id, const
 void FSFloaterIMContainer::tabOpen(LLFloater* opened_floater, bool from_click)
 {
     LLEmojiHelper::instance().hideHelper(nullptr, true);
+
+    mFlashingTabStates.erase(opened_floater);
+}
+
+void FSFloaterIMContainer::startFlashingTab(LLFloater* floater, const std::string& message)
+{
+    const bool contains_mention = LLUrlRegistry::getInstance()->containsAgentMention(message);
+
+    auto& [session_floater, is_alt_flashing] = *(mFlashingTabStates.try_emplace(floater, false).first);
+    is_alt_flashing = is_alt_flashing || contains_mention;
+
+    if (LLMultiFloater::isFloaterFlashing(floater))
+    {
+        LLMultiFloater::setFloaterFlashing(floater, false);
+    }
+    LLMultiFloater::setFloaterFlashing(floater, true, is_alt_flashing);
 }
 // EOF
diff --git a/indra/newview/fsfloaterimcontainer.h b/indra/newview/fsfloaterimcontainer.h
index af7ebdec35..50b9b36d1f 100644
--- a/indra/newview/fsfloaterimcontainer.h
+++ b/indra/newview/fsfloaterimcontainer.h
@@ -63,7 +63,7 @@ public:
     virtual void setVisible(bool b);
     /*virtual*/ void setMinimized(bool b);
 
-    void onNewMessageReceived(const LLSD& data); // public so nearbychat can call it directly. TODO: handle via callback. -AO
+    void onNewMessageReceived(const LLSD& msg); // public so nearbychat can call it directly. TODO: handle via callback. -AO
 
     virtual void sessionAdded(const LLUUID& session_id, const std::string& name, const LLUUID& other_participant_id, bool has_offline_msg);
     virtual void sessionActivated(const LLUUID& session_id, const std::string& name, const LLUUID& other_participant_id) {};
@@ -78,6 +78,8 @@ public:
 
     void tabOpen(LLFloater* opened_floater, bool from_click);
 
+    void startFlashingTab(LLFloater* floater, const std::string& message);
+
 private:
     enum eVoiceState
     {
@@ -105,6 +107,8 @@ private:
 
     bool        mIsAddingNewSession;
 
+    std::map<LLFloater*, bool> mFlashingTabStates;
+
 // [SL:KB] - Patch: UI-TabRearrange | Checked: 2012-05-05 (Catznip-3.3.0)
 protected:
     void onIMTabRearrange(S32 tab_index, LLPanel* tab_panel);
diff --git a/indra/newview/fsfloaternearbychat.cpp b/indra/newview/fsfloaternearbychat.cpp
index 67f8c6b34d..80e58347e8 100644
--- a/indra/newview/fsfloaternearbychat.cpp
+++ b/indra/newview/fsfloaternearbychat.cpp
@@ -276,11 +276,11 @@ void FSFloaterNearbyChat::addMessage(const LLChat& chat,bool archive,const LLSD
     // AO: IF tab mode active, flash our tab
     if (isChatMultiTab())
     {
-        LLMultiFloater* hostp = getHost();
         // KC: Don't flash tab on system messages
-        if (!isInVisibleChain() && hostp && (chat.mSourceType == CHAT_SOURCE_AGENT || chat.mSourceType == CHAT_SOURCE_OBJECT))
+        if (FSFloaterIMContainer* container = dynamic_cast<FSFloaterIMContainer*>(getHost());
+            !isInVisibleChain() && container && (chat.mSourceType == CHAT_SOURCE_AGENT || chat.mSourceType == CHAT_SOURCE_OBJECT))
         {
-            hostp->setFloaterFlashing(this, true);
+            container->startFlashingTab(this, chat.mText);
         }
     }
 
diff --git a/indra/newview/llimview.cpp b/indra/newview/llimview.cpp
index 4c88a4b814..37895abff6 100644
--- a/indra/newview/llimview.cpp
+++ b/indra/newview/llimview.cpp
@@ -468,7 +468,6 @@ void notify_of_message(const LLSD& msg, bool is_dnd_msg)
             && gSavedSettings.getBOOL("FSNotifyNearbyChatFlash"))
         {
             im_container->addFlashingSession(session_id);
-            gToolBarView->flashCommand(LLCommandId("chat"), true, im_container->isMinimized());
         }
         return;
     }
@@ -492,7 +491,6 @@ void notify_of_message(const LLSD& msg, bool is_dnd_msg)
         && gSavedSettings.getBOOL("FSNotifyIMFlash"))
     {
         im_container->addFlashingSession(session_id);
-        gToolBarView->flashCommand(LLCommandId("chat"), true, im_container->isMinimized());
     }
 
         // <FS:Ansariel> (Group-)IMs in chat console
diff --git a/indra/newview/skins/ansastorm/colors.xml b/indra/newview/skins/ansastorm/colors.xml
index 882ca15d06..83300c00ae 100644
--- a/indra/newview/skins/ansastorm/colors.xml
+++ b/indra/newview/skins/ansastorm/colors.xml
@@ -1437,4 +1437,7 @@
   <color
     name="ChatSelfMentionHighlight"
     value="1 1 0.383 1" />
+  <color
+    name="MentionFlashBgColor"
+    reference="EmphasisColor" />
 </colors>
diff --git a/indra/newview/skins/ansastorm/themes/blood/colors.xml b/indra/newview/skins/ansastorm/themes/blood/colors.xml
index b24d4988f7..8fa84ec3d3 100644
--- a/indra/newview/skins/ansastorm/themes/blood/colors.xml
+++ b/indra/newview/skins/ansastorm/themes/blood/colors.xml
@@ -1190,4 +1190,7 @@
   <color
      name="NotecardCursorColor"
      reference="TextCursorColor" />
+  <color
+    name="MentionFlashBgColor"
+    reference="EmphasisColor" />
 </colors>
diff --git a/indra/newview/skins/ansastorm/themes/classic_brown/colors.xml b/indra/newview/skins/ansastorm/themes/classic_brown/colors.xml
index 7b4d059737..f2b592947a 100644
--- a/indra/newview/skins/ansastorm/themes/classic_brown/colors.xml
+++ b/indra/newview/skins/ansastorm/themes/classic_brown/colors.xml
@@ -1430,4 +1430,7 @@
   <color
     name="ChatSelfMentionHighlight"
     value="1 1 0.734 1" />
+  <color
+    name="MentionFlashBgColor"
+    reference="EmphasisColor" />
 </colors>
diff --git a/indra/newview/skins/ansastorm/themes/ectoplasma/colors.xml b/indra/newview/skins/ansastorm/themes/ectoplasma/colors.xml
index 39c6ad5bd0..1bf7400ef2 100644
--- a/indra/newview/skins/ansastorm/themes/ectoplasma/colors.xml
+++ b/indra/newview/skins/ansastorm/themes/ectoplasma/colors.xml
@@ -1178,4 +1178,7 @@
   <color
      name="NotecardCursorColor"
      reference="TextCursorColor" />
+  <color
+    name="MentionFlashBgColor"
+    reference="EmphasisColor" />
 </colors>
diff --git a/indra/newview/skins/default/xui/en/widgets/button.xml b/indra/newview/skins/default/xui/en/widgets/button.xml
index 7b2476fcf2..1722a5475a 100644
--- a/indra/newview/skins/default/xui/en/widgets/button.xml
+++ b/indra/newview/skins/default/xui/en/widgets/button.xml
@@ -18,6 +18,7 @@
         image_color="ButtonImageColor"
         image_color_disabled="ButtonImageColor"
         flash_color="ButtonFlashBgColor"
+        flash_alt_color="MentionFlashBgColor"
 	font="SansSerifSmall"
         hover_glow_amount="0.25"
         halign="center"
diff --git a/indra/newview/skins/starlightcui/xui/en/widgets/button.xml b/indra/newview/skins/starlightcui/xui/en/widgets/button.xml
index 0c60fc06cb..627feeff18 100644
--- a/indra/newview/skins/starlightcui/xui/en/widgets/button.xml
+++ b/indra/newview/skins/starlightcui/xui/en/widgets/button.xml
@@ -18,6 +18,7 @@
         image_color="SL-CustomMain"
         image_color_disabled="ButtonImageColor"
         flash_color="SL-CustomMain"
+        flash_alt_color="MentionFlashBgColor"
         font="SansSerifSmall"
         hover_glow_amount="0.25"
         halign="center"