modifierControl constant Null safety
This mask is used to check the RawKeyEventDataLinux.modifiers field to test whether one of the CTRL modifier keys is pressed.
Use this value if you need to decode the RawKeyEventDataLinux.modifiers field yourself, but it's much easier to use isModifierPressed if you just want to know if a modifier is pressed. This is especially true on GTK, since its modifiers don't include the effects of the current key event.
static const int modifierControl = 1 << 2;