Hi. Do you mean that this scene doesn’t work when multiple monitors are connected? I just didn’t fully understand your wording, sorry :D. You need to shake the icon within the game window, yes. If you move the mouse outside the game, Ren’Py indeed won’t register it.
When multiple monitors are connected, shaking vigorously becomes a futile effort because the amount of movement required in such a short time means it's impossible to do without accidentally moving the mouse over to a different monitor.
Likewise the black bars that cover the rest of the window when resized to a different aspect ratio than the game render (such as when maximized/fullscreen on an ultrawide monitor) also interrupt the input.
Block areas being unresponsive is probably more of a technical problem in the engine rather than something necessarily dependent on my setup. But it was consistently registering only about 1 in every 3 clicks, even with the game running at less than 10% CPU and 5% GPU.
It also rather frequently seemed like Katharine would attack in the middle of the parry animation, but that was more of an annoyance than a gamebreaking issue.
I just tried going through this segment in fullscreen mode for the first time. I do have a second monitor, and I can move the cursor onto it without minimizing the game. I completed this segment without any issues, since you don’t need to shake the icon across the entire screen. Moving the mouse back and forth within about 1 cm is enough to clear this scene.
That brings up another question about your monitor — it’s not a 16:9 aspect ratio, right? Are you running the game in fullscreen on a monitor with an aspect ratio wider than 16:9?
It doesn't minimize the game, but when the cursor leaves the active portion of the game window, the parry button freezes in place. Ren'Py is then slow to register when the cursor re-enters the window, leading to at least a quarter second delay before you can continue shaking the button, which is damning when you have such a short time to perform the mechanic.
I ended up having to disable my other monitors in order to finish the mission.
Yes, specifically it's 21:9, so when playing a 16:9 game there's always a lot of blacked out screen space.
Fullscreen isn't really part of the issue. If anything it slightly helps, because it slightly reduces the amount of unused space.
I normally play just maximized, but had to turn on fullscreen for this just to get that little bit of extra active render area.