After a Vivado or SDAccel installation I can see that the Xilinx Information Center (XIC) process remains active (running) in the background.
It is represented by a small icon on the screen.
If I open the XIC by double-clicking on the icon, I see that the opened XIC dialog box is not resizable.
As a result all action buttons located on the right of the XIC window are hidden.
This issue has been seen on CentOS 6.8 and CentOS 7.2.
In order to correctly use XIC in this case, you will need to open the non resizable window, then exit it, and after that restart XIC.
The procedure to achieve this depends on the CentOS version you use.