Hi Mikasa,
thank you for the suggestions. New ideas are always appreciated, so feel free to post further improvements, that come to your mind. The “OGS Development” category is the right place to post your suggestions, so no worries.
If you want to have further categories added, this is the place to go: What topic categories should we add/remove/change?
As for the re-post, the current time of the Devs is invested greatly into finishing the next major 4.0 update of the website. Publishing, maintaining and updating a development list surely is a nice thing, but will only keep them distracted. So having an idea re-posted in this forums isn’t a big deal for us. Just keep the ideas coming. 
I am not sure, if I understand the “decline button” question right. When you notice your opponent is not at his computer, you can cancel or pause the game right away. (Which you prefer). The downside of pausing is, that your opponent can resume the pause, even when you are gone. As for canceling, neither of the two players will lose the game, or rank, if it is done within the first 19 moves. (For 19x19). Feel free to cancel the game right away when your opponent is not there. You can also check out the user-list, which shows you if your opponent is actually in the game.
I have included a picture on where to find the user-list below the post!
For the karma system, I would like to invite you to this topic: Advise to add the rating users function after each game
Feel free to add your thoughts on a user-rating system there, it is appreciated!
I like your idea of a better visualization of the wins/losses, but I am not sure if it’s not already in 4.0. Maybe one of the Developers can clarify this!
I hope this helped you out a little!
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Click on the button in the red circle to see users in a game.
