The functionality of that is not hard at all. A few checkboxes, a trackbar, and a hotkey control (there is actually a standard Win32 control for this: https://learn.microsoft.com/en-us/windows/win32/controls/hot... ), with "pushlike" checkboxes at the top to be drawn replicating the monitor layout.

But that "modern" style is... disgusting and repulsive. That whole dialog is bigger than one of my monitors due to how much wasted space it has.

My favourite example of "Modern" style is the toggle switch, shown even in that image. I laugh a lot of the times I see one, it's the 'replacement' for the checkbox, but it's so awful at actually telegraphing it's current state in a consistent way- (the entire purpose of the control!) that it has to have a label indicating whether it's on or off. I find it so absurd that people genuinely put this stuff into their programs and have no problem with it, because apparently we are just supposed to accept this type of poorly designed component because it's more "Modern".