Interface for mouse events.
| actionKey | Returns true if the platform specific action key is pressed. This key is Command on macOS and Control otherwise. |
| altKey | Return true if the Alt key is pressed. |
| button | Integer representing the pressed mouse button: 0 is left, 1 is right, 2 is center. |
| clickCount | Number of clicks. |
| commandKey | Return true if the Windows/Command key is pressed. |
| ctrlKey | Return true if the Control key is pressed. |
| localMousePosition | The mouse position in the current target coordinate system. |
| modifiers | Flag set holding the pressed modifier keys (Alt, Control, Shift, Windows/Command). |
| mouseDelta | Mouse position difference between the last mouse event and this one. |
| mousePosition | The mouse position in the panel coordinate system. |
| shiftKey | Return true if the Shift key is pressed. |