Event Viewer: Upon treeview change, buttons are updated but not other fields

reactos-bootcd-0.4.16-dev-799-g1786a68-x86-gcc-lin-dbg

• Following fix of CORE-19786
• In Event viewer, click on "Application log"
• An item gets displayed in the lower part, scroll buttons are enabled
• Change to "Security log" (no items)
• Scroll buttons gets disabled but content remains displayed, while not from the opened log
• Expected behavior: others fields to be reset or 1 item of the log to be loaded