Hello!
On mac when you click fullscreen mode QToolBar will show double. We reported a bug:
https://bugreports.qt-project.org/browse/QTBUG-41679?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
... but it have a low priority. We cannot wait longer must solve this.
Anybody have any idea in this case?
