help

is addEventHandler("onClientRender",root,anyfunction) makes a DX things visible for all players in the server and when using removeEventHandler will make them invisible for all players who see them?!

Yes, you've to use addEventHandler to let your dirext x shows and removeEventHandler to make them invisible.

LOL i mean for all players or one player?! i tried addEventHandler("onClientRender,player,function) but didn't work

LOL i mean for all players or one player?! i tried addEventHandler("onClientRender,player,function) but didn't work

You've to check if the player who hitting marker is a localPlayer.

Example:

function MarkerHit(hitPlayer,matchingDimension) 
 if( hitPlayer == localPlayer ) then 
guiSetVisible (windowname,true) 
showCursor (true) 
    end 
end 
addEventHandler ("onClientMarkerHit",Marker,MarkerHit) 

LOL i mean for all players or one player?! i tried addEventHandler("onClientRender,player,function) but didn't work

You've to check if the player who hitting marker is a localPlayer.

Example:

function MarkerHit(hitPlayer,matchingDimension) 
 if( hitPlayer == localPlayer ) then 
guiSetVisible (windowname,true) 
showCursor (true) 
    end 
end 
addEventHandler ("onClientMarkerHit",Marker,MarkerHit) 

What marker?!

That's just a example.

but it isn;t about onClientRender

but it isn;t about onClientRender

Just use if( hitPlayer == localPlayer ) then and enjoy