For our project, we want to open our electron app from tray with a keypress on "Scroll Lock" (js keycode 145) but this is no registered accelerator that we can use.
atom/common/keyboard_util.cc
c = base::ToLowerASCII(c);
  *shifted = false;
  switch (c) {
    case 0x08:
      return ui::VKEY_BACK;
    case 0x7F:
      return ui::VKEY_DELETE;
    case 0x09:
      return ui::VKEY_TAB;
    case 0x0D:
      return ui::VKEY_RETURN;
    case 0x1B:
      return ui::VKEY_ESCAPE;
    case ' ':
      return ui::VKEY_SPACE;
    case 'a':
      return ui::VKEY_A;
    case 'b':
      return ui::VKEY_B;
    case 'c':
      return ui::VKEY_C;
    case 'd':
      return ui::VKEY_D;
    case 'e':
      return ui::VKEY_E;
    case 'f':
      return ui::VKEY_F;