Now that we have support for 10-bit per channel in both the server (#909) and the client (#1309), 10-bit video encoding is planned (#1308 for nvenc, #1310 for vpx) so it makes sense to also support a 10-bit non-video compression format. See also #784 for BPG.
EXR also supports stereo modes (#1316) and could potentially help us replace PNG with something faster / better? The list of Compression methods is not particularly impressive: RLE and ZIP for lossless!
Both openexr and jxrlib have mingw64 ports already.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/1441