Got it. Thanks!Actually having influence cost for decline offer is not accepted so this problem partly lost its importance. If influence cost was not removed my solution was to pause game and force pop up to appear (like player clicked) (only if player did not open it for 24 hours). Now this is not needed. If player do not open notification at given time period (24 hours) he will lose opportunity of checking offer.
If player is not king and if he is vassal and he do not open notification pop up we can directly start peace voting when 24 hour time period is past.
In that case, since the notification is time sensitive, it might be helpful to have an indication of how much time we have remaining to respond to the offer before it expires or voting starts without you. It could be as simple as a tooltip on the notification stating something like "You have 18 hours remaining to respond to this offer," or a visual on the notification itself, such as:
It could also be used for other time sensitive notifications such as settlement voting, etc. @MRay How hard would it be to add something like that?