When ''Always in tray'' is enabled, by default (when "SingleClickTray" isn't enabled), a single-click will bring XMPlay to the front if it is not currently minimized. Basically, it should work like this...
SingleClickTray disabled: single-click brings to front, double-click minimizes
SingleClickTray disabled + minimized: single-click does nothing, double-click restores
SingleClickTray enabled: single-click minimizes
SingleClickTray enabled + minimized: single-click restores
If that is not what you're seeing, please describe which scenarios are behaving differently and how.