has anyone seen any dps meters like in wow for lineage 2?
so you can see who is doing more dmg to a boss or something?

client side? cant be done, as you are not aware of whats the damage of other players (could be done only for your char)
server side? i guess its been done already (saw it on h5 javas i believe) if i remember correctly you could shift+click the mob and select agro tab which showed the damage each player dealt and agro it generated

I confirm. Client doesn't get info of damage of other players.

Something like this https://typhoonandrew.files.wordpress.com/2013/09/5-4-dps-rank-553-gear.png you can easily make in Npc window or Community Board window. 

so if i make a window is it possible to update data sent by server and show them to that window?
for example, every time you deal damage to the boss it updates and shows the data server sends?
what is your opinion on that?

Yes, that can be done.

For L2Tales in Clan Window i have added button which shows bars(similar to yours but vertical, not horizontal) with online time of each member.

 

You should be aware that if you want to make it in completely new window, you dont have many options of who can make such thing and price will be a lot bigger than showing it in Npc Window or Community Board. 

i see, thank you for the feedback. i'll let you know if i manage to do it ;)