NotImplementedExcetion for callbacks

[larkliy]

This problem occurs when connecting the latest version of Imgui .NET:

This problem is on the latest version for x86 assemblies only. For x64, everything still works.

This problem for x86 is solved when I downgrade from 1.91.6.1 to the next-to-last: 1.91.0.1:

Why is this so?

[CasualPokePlayer]

The exact error is more a red herring, the issue is that a few types are incorrect and end up being the wrong size under x86, most notably ImTextureID (see #509), so structs relying on its size (such as ImDrawCmd, which has to be used by any ImGui application) will be mismatched from the unmanaged struct. ImTextureID was previously correct in older versions (mapping to void*, so IntPtr size), but unmanaged side changes in recent updates that made it so it is always 64 bits (on x64 this changes nothing, but on x86 IntPtr will be 32 bits now)