On listitem and titlebar elements, mouse events normally do not get sent to their children; instead they are retargeted to the listitem and titlebar element itself. This means that elements placed inside a listitem do not respond to events, and instead clicking the mouse simply selects that item within the list. By setting the allowevents attribute to true, this special behavior is disabled, and the events are targeted the same as other elements.

For menu, menuseparator, menuitem and treecol elements, as well as menu buttons, and the popup datepicker, mouse events are also retargeted to the element itself. However, the allowevents attribute is handled in a different way. Instead, the allowevents may be set to true on a descendant instead. This does the same thing in that it allows events to be targeted normally, but allows this to be different for each descendant.

This behavior is used for menus, for instance, to allow a menu button to behave as a menu when clicking on it, yet have part of the menu behave as a button. For the latter, the allowevents attribute is set to true to have a click on the child button receive events instead of targeting all events at the menu.