Below is the image screenshot I took on when I clicked on event. 
When I reduced the size of the browser, it becomes partially visible as follows
This same problem occurs with few other things such as when quiz is added, the HTML editor would block the word Summary or quiz description behind it unless the size of the browser is reduced. Does this problem occurs due to the theme that we are using?
In reply to Noorazlan Ahmad Yaacob
Re: Gear buttons hidden on when clicked on event
de Marcus Green -
I know nothing about this particular issue, but I know that anyone who can help you will need more information. In particular which version of Moodle are you running and what is the theme.
In reply to Marcus Green
Re: Gear buttons hidden on when clicked on event
The theme we are using is called Contemporary, and our moodle version is Moodle 3.0.3.