Complications with Cross-Platform Input Handling

It was bound to happen eventually, but the input handling module is the first part of the project to display different behavior across platforms. winit provides a fairly solid basis for input handling, but Windows and Linux differ in terms of what sort of event is delivered to the program.

Initially, I used WindowEvents for everything. This works perfectly well for keystrokes and mouse clicks, but mouse movement may still have acceleration applied, which is undesirable for camera control. winit also offers DeviceEvents for this purpose. I tried just handling mouse movement with raw input, keeping all other inputs in WindowEvents, but it seems that handling DeviceEvents on Linux causes the WindowEvents to be eaten.

The next obvious solution is to simply handle everything with DeviceEvents, but this presents additional problems. First, Windows doesn't seem to even deliver keyboard input as a DeviceEvent -- keyboard input still needs to be polled as a WindowEvent. It also means that window focus has to be handled manually, since DeviceEvents are delivered regardless of whether the window is focused or not.

To add to the complexity of this problem, apparently not all window managers are well-behaved when it comes to determining focus. I run i3wm on my Linux install, and it doesn't deliver WindowEvent::Focused events when toggling focus or switching workspaces. This will have to remain an unsolved problem for the time being.