hide party frame when player join in combat

[oXid_FoX]

hello everybody !

I wrote a small addon to hide the party frame.
the whole code:

function oxPartyFrameHider_OnEvent(this, event)
	if GetNumPartyMembers() > 0 then
		HidePartyFrame()
	end

end

local frame = CreateFrame("Frame","oxPartyFrameHider",UIParent)
frame:SetScript("OnEvent", oxPartyFrameHider_OnEvent)
frame:RegisterEvent("PARTY_MEMBERS_CHANGED")

pretty simple, isn't it ?

but... there is a "bug": when a player join the party when we are in combat, the party frame appears...
the only solution I've found: the PARTY_MEMBERS_CHANGED event must be fired one more time (basically, it means a player must leave/join the party).

how could I fix that ?
thanks for your help, and sorry for my poor english...