| x | The value of the x coordinate (in layer display coordinates) of the position where the mouse button was pressed. |
| y | The value of the y coordinate (in the display coordinates of the layer) of the position where the mouse button was pressed. |
| button | The mouse button that was pressed. One of the following values: mbLeft : Left mouse button pressed mbMiddle : Middle mouse button pressed mbRight : Right mouse button pressed mbX1 : The first button of the mouse's side key is pressed mbX2 : The second button of the mouse's side key is pressed |
| shift | The state of the shift key that was pressed at the same time when the mouse button was pressed.
It is a combination of the following values by bit OR. ssAlt : ALT key was pressed ssShift : SHIFT key was pressed ssCtrl : CTRL key was pressed |