Static Window Close - Chat
These options are used to either Disable or Enable the CLOSE button on the Chat window.
The Chat window is a static window that is will always appear when you rezone or relog. This option gives you the ability to temporarily close the window if needed by enabling the CLOSE button in the upper right hand corner of the window.
Chat window with CLOSE button disabled is shown below.

Chat window with CLOSE button enabled is shown below.