CTRL key "hi-jacked" by keybinder on Linux

[brotherJ4mes]

Not sure if this is an actual bug or expected behavior but I've noticed an issue with the inability to use the CTRL key with keybinder enabled...

For example, with keybinder off, I'm able to use the EMACS bindings in FF: ctrl+a=beginning of line, ctrl+u=clear line, ctrl+e=end of line, etc.. As soon as I enable keybinder, most of these fail (with the exception of ctrl+e for some reason.) Two more examples that are probably less obscure to most folks are ctrl+b, ctrl+i in gmail (bold and italicize, respectively) and ctrl+m in google slides (new slide). These all seem to work fine with keybinder disabled but as soon as I enable it they fail.

I have made sure there are no conflicts with my keybinder shortcut mappings and even gone so far as to disable or remap ALL shortcuts that involve the CTRL key (i.e. none of my enabled shortcuts in keybinder use ctrl) and I experience the same issue.

Is this expected behavior or a bug? Any suggested workarounds? XUL keys?

version info: Firefox ESR 52.8.0 (64-bit) System: Centos7, Gnome3

edit: I also just realized when experimenting that I'm actually not able to use ctrl in my shortcut mappings. If I double click any command attempt to assign it to ctrl+... the shortcut reverts to whatever it was as soon as I down press the ctrl button.