Vertical position (or Y coordinate) in pixels of the mouse in relation to the top left corner or the Clickable Image control on which the left mouse button was pressed.
This value is undefined if ImageYPos is used in an event other than the click code of a clickable image whose type is "Click area - Send the click coordinates to the server". This value is undefined if ImageYPos is used in an event other than the click code of a Clickable Image control, whose action is "Send the click coordinates to the server" (in the "Details" tab of the control description window).