Wayland compositors may send recursive clipboard offers to the client, which need to be filtered out to avoid clearing local data. Previously this was worked around with a hack, but this caused the ownership flag to be set incorrectly, which broke some clients.
This introduces a metadata MIME type of application/x-sdl3-source-id to be sent with SDL3 selection offers, which contains a string that is a unique identifier for the instance, and can be used to detect if a received selection offer is originating from the same instance that generated it.
If DBus is available, the unique identifier string is the unique name of the connection, otherwise, the process ID is used.
If a window isn't resizable from specific directions, the compositor can inform clients of the current edge constraints, so they don't display resize cursors for non-resizable edges.
Wayland environments can expose more than one seat for multiple collections of input devices, which can include multiple, simultaneously active, desktop pointers and keyboards with independent layouts. The Wayland input backend previously presumed that only one seat could exist, which caused broken behavior if the compositor exposed more than one, which is possible on wlroots based compositors such as Sway. This introduces support for handling multiple seats, including proper handling of dynamically added and removed seats and capabilities at run time.
The SDL Wayland input system was accreted over time, and the assumption that only one seat will ever exist resulted in state and related objects not always being tied to their most appropriate owner in a multi-seat scenario, so refactoring was required to manage several bits of state per-seat, instead of per-window or globally.
As Wayland keyboards can have per-seat layouts, fast keymap switching is required when multiplexing input from multiple seats to the global SDL keyboard device. A parameter was added to the keymap creation function to specify if the keymap lifetime should be externally managed to facilitate keymap reuse, and some layout info was moved from the global keyboard state to the keymap state to avoid unnecessarily redetermining it whenever a reused keymap is bound. This reduces the overhead of switching keymaps to setting a single pointer.
Multiple seats also means that multiple windows can have keyboard and/or mouse focus at the same time on some compositors, but this is not currently a well-handled case in SDL, and will require more work to support, if necessary.
Fix IMU timing stamp - simulate the timing stamp from the controller hardware's perspective, as opposed to the receiving computer's perspective. Do this by advancing a time stamp by a fixed rate, based on observation of average rate over bluetooth.
This reverts commit 5a59b5f321.
The strong ABI guarantee only applies if bool is a byte (we repurposed a Uint8 field as a bool in SDL_gpu.h), and 32-bit PPC isn't a platform we support, so I'm going to back this patch out.
