minor message buffer improvements

internal/ui/messages/container/compact/compact.go

@@ -19,7 +19,10 @@ func NewContainer(ctrl container.Controller) *Container {
 }
 
 func (c *Container) CreateMessage(msg cchat.MessageCreate) {
-	gts.ExecAsync(func() { c.GridContainer.CreateMessageUnsafe(msg) })
+	gts.ExecAsync(func() {
+		c.GridContainer.CreateMessageUnsafe(msg)
+		c.GridContainer.CleanMessages()
+	})
 }
 
 func (c *Container) UpdateMessage(msg cchat.MessageUpdate) {

internal/ui/messages/container/container.go

@@ -101,15 +101,23 @@ func NewGridContainer(constr Constructor, ctrl Controller) *GridContainer {
 	}
 }
 
-// CreateMessageUnsafe inserts a message as well as cleaning up the backlog if
+// CreateMessageUnsafe inserts a message. It does not clean up old messages.
-// the user is scrolled to the bottom.
 func (c *GridContainer) CreateMessageUnsafe(msg cchat.MessageCreate) {
 	// Insert the message first.
 	c.GridStore.CreateMessageUnsafe(msg)
+}
 
+// CleanMessages cleans up the oldest messages if the user is scrolled to the
+// bottom. True is returned if there were changes.
+func (c *GridContainer) CleanMessages() bool {
 	// Determine if the user is scrolled to the bottom for cleaning up.
 	if c.Bottomed() {
 		// Clean up the backlog.
-		c.DeleteEarliest(c.MessagesLen() - BacklogLimit)
+		if delta := c.MessagesLen() - BacklogLimit; delta > 0 {
+			c.DeleteEarliest(delta)
+			return true
 		}
+	}
+
+	return false
 }

internal/ui/messages/container/cozy/cozy.go

@@ -134,7 +134,7 @@ func (c *Container) CreateMessage(msg cchat.MessageCreate) {
 
 		// Did the handler wipe old messages? It will only do so if the user is
 		// scrolled to the bottom.
-		if c.Bottomed() {
+		if c.GridContainer.CleanMessages() {
 			// We need to uncollapse the first (top) message. No length check is
 			// needed here, as we just inserted a message.
 			c.uncompact(c.FirstMessage())