messagebartextarea: tab should focus next item

Change-Id: I5d15ad9b8019fc1c758224bccd024679288bec98
GitLab: #1055

src/app/mainview/components/MessageBarTextArea.qml

@@ -119,6 +119,9 @@ JamiFlickable {
                     root.sendMessagesRequired()
                     keyEvent.accepted = true
                 }
+            } else if (keyEvent.key === Qt.Key_Tab) {
+                nextItemInFocusChain().forceActiveFocus(Qt.TabFocusReason)
+                keyEvent.accepted = true
             }
         }
     }