ISSUE
If you mimimize / close the Steam client and then restore the window, the most recently clicked window button (Minimize / Close) will be highlighted (focused) for a moment.

If you minimize / close by other methods (keyboard, taskbar), the maximize / restore button flickers between states on restore (sometimes).

These issues only happen when restoring to the Library view.
If you restore to a webpage (e.g. storepage or forum), no abnormal behavior occurs.

OS
Windows 10

STEPS
Go to the Library view.
Click on the "Close" button in the top right.
Restore the window by any method (e.g. doubleclick tray icon)

RESULTS
For a second the "Close" button appears red (as if hovered / focused).

EXPECTED
The "Close" button does not become focused / appear red.