« XUL Reference home
Type: one of the values below
Determines whether mouse events are passed to the element or not. If this attribute is not specified, the value is inherited from the parent of the element. If no ancestor has the mousethrough attribute set, the default value is never.
Mouse events are transparent to the element. This means that the element will not receive any mouse events due to either clicking or movement. Child elements may override this if they specify mousethrough="never".
Mouse events are passed to the element as normal.

The mousethrough attribute is typically used in conjunction with a stack to allow elements to be stacked above other elements yet allow mouse events to be sent to lower elements. In the following example, the image appears above the button, yet the mousethrough attribute specified on the image causes mouse events to be ignored on the image and instead fall through to the button. If the mousethrough attribute was not used, the image would receive all mouse events and the button could not be pressed with the mouse.

  <button label="Below"/>
  <image src="happy.png" mousethrough="always"/>