kMiddleMouseButton top-level constant Null safety
The bit of PointerEvent.buttons that corresponds to the middle mouse button.
The middle mouse button is typically between the left and right buttons on the top of the mouse but can be reconfigured to be a different physical button.
- kTertiaryButton, which has the same value but describes its cross-device concept.
const int kMiddleMouseButton = kTertiaryButton;