Wait for smooth scrolling animation to add new message (#2084)

Co-authored-by: Paweł <zneix@zneix.eu>
Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

src/widgets/helper/ChannelView.cpp

@@ -785,6 +785,18 @@ void ChannelView::messageAppended(MessagePtr &message,
     this->lastMessageHasAlternateBackground_ =
         !this->lastMessageHasAlternateBackground_;
 
+    if (!this->scrollBar_->isAtBottom() &&
+        this->scrollBar_->getCurrentValueAnimation().state() ==
+            QPropertyAnimation::Running)
+    {
+        QEventLoop loop;
+
+        connect(&this->scrollBar_->getCurrentValueAnimation(),
+                &QAbstractAnimation::stateChanged, &loop, &QEventLoop::quit);
+
+        loop.exec();
+    }
+
     if (this->messages_.pushBack(MessageLayoutPtr(messageRef), deleted))
     {
         if (this->paused())