[Mac OS port] Potential issues with keyboard modifier state

[jceipek]

In my MacOS port, I've been noticing issues where the application didn't realize I was holding down certain modifier keys.
I believe the cause is that the modifier state isn't being appropriately synchronized here: https://github.com/dfeneyrou/palanteer/blob/main/server/viewer/vwPlatform.cpp#L642-L718

Note that the kms parameter is ignored in many of the functions in the file, which can lead to these imgui fields not being synchronized to the keyboard state correctly:

io.KeyCtrl
io.KeyShift
io.KeyAlt  
io.KeySuper

I also haven't been able to determine which osHandler->event* function would be best to call when responding to the NSEventTypeFlagsChanged event type on macOS. See https://github.com/ocornut/imgui/blob/0b8a2470743f89d19ab2d5920606434b604b529e/backends/imgui_impl_osx.mm#L342-L345 for how it is handled in the Dear ImGui example.

[dfeneyrou]

See answer in #18 .
I cannot help for Mac OS related questions because I have no such environment at hand nor experience with it.
However, Dear Imgui contains valuable information for this kind of project in its various examples.

[jceipek]

@dfeneyrou What are your thoughts on adding this? https://github.com/dfeneyrou/palanteer/pull/21/files#diff-2d88bc2cf5369b76a592e61c044242925375802ffdcbcbf8440711355359fe76R695-R707

And do you think it makes sense to add something like

     io.KeyCtrl  = kms.ctrl;
     io.KeyShift = kms.shift;
     io.KeyAlt   = kms.alt;
     io.KeySuper = kms.sys;

to all of the vwPlatform.cpp functions that accept kms parameters but ignore them?