This API and implementation comes from the Unreal Engine branch of SDL, which
originally called this "SDL_ConfineCursor".
Some minor cleanup and changes for consistency with the rest of SDL_video, but
there are two major changes:
1. The coordinate system has been changed so that `rect` is _window_ relative
and not _screen_ relative, making it easier to implement without having
global access to the display.
2. The UE version unset all rects when passing `NULL` as a parameter for
`window`, this has been removed as it was an unused feature anyhow.
Currently this is only implemented for X, but can be supported on Wayland and
Windows at minimum too.
This prevents conflicts with hidapi linked with applications, as well as allowing applications to make use of HIDAPI on Android and other platforms that might not normally have an implementation available.
Enabling the RawInput backend causes SDL_XINPUT_Enabled() to return false.
That causes WGI and DInput backends to take ownership of XInput-compatible
controllers, because they think there's no XInput-specific backend enabled.
In WGI's case, it will actually race with RawInput to open the device. By
properly excluding XInput devices from WGI, we can ensure that the sets of
devices managed by WGI and RawInput don't intersect. This makes the race
harmless, since they'll never both go after the same device.
The Xbox One driver stack doesn't propagate the VID/PID down to the
HID devices that end up in the GetRawInputDeviceList() output. This
means we end up matching against the wrong VID/PID and can't properly
exclude Xbox One controllers from WGI.
Fortunately, it is possible to walk back up the device tree to find
the parent with the matching VID/PID.
"If your app targets Android 12, you must specify the mutability of each PendingIntent object that your app creates. This additional requirement improves your app's security."
FLAG_IMMUTABLE was added in API 23 so that's why I'm using "> API 23". Using API 30 would also fix the Android 12 issue. Alternatively if PendingIntents should be mutable you could change it to "FLAG_MUTABLE".
In this case we'll get WM_KILLFOCUS when the child window is focused, but we'll retain focus on the top level window, but when we Alt-Tab away, we won't get another WM_KILLFOCUS or WM_NCACTIVATE, we get WM_ACTIVATE instead, so we need to check for focus updates in response to that as well.