##<iron-overlay-backdrop>
iron-overlay-backdrop is a backdrop used by Polymer.IronOverlayBehavior. It should be a singleton.
Styling
The following custom properties and mixins are available for styling.
| Custom property | Description | Default |
|---|---|---|
--iron-overlay-backdrop-background-color | Backdrop background color | #000 |
--iron-overlay-backdrop-opacity | Backdrop opacity | 0.6 |
--iron-overlay-backdrop | Mixin applied to iron-overlay-backdrop. | {} |
--iron-overlay-backdrop-opened | Mixin applied to iron-overlay-backdrop when it is displayed | {} |
##Polymer.IronOverlayBehavior
Use Polymer.IronOverlayBehavior to implement an element that can be hidden or shown, and displays on top of other content. It includes an optional backdrop, and can be used to implement a variety of UI controls including dialogs and drop downs. Multiple overlays may be displayed at once.
Closing and canceling
A dialog may be hidden by closing or canceling. The difference between close and cancel is user intent. Closing generally implies that the user acknowledged the content on the overlay. By default, it will cancel whenever the user taps outside it or presses the escape key. This behavior is configurable with the no-cancel-on-esc-key and the no-cancel-on-outside-click properties. close() should be called explicitly by the implementer when the user interacts with a control in the overlay element. When the dialog is canceled, the overlay fires an ‘iron-overlay-canceled’ event. Call preventDefault on this event to prevent the overlay from closing.
Positioning
By default the element is sized and positioned to fit and centered inside the window. You can position and size it manually using CSS. See Polymer.IronFitBehavior.
Backdrop
Set the with-backdrop attribute to display a backdrop behind the overlay. The backdrop is appended to <body> and is of type <iron-overlay-backdrop>. See its doc page for styling options.
Limitations
The element is styled to appear on top of other content by setting its z-index property. You must ensure no element has a stacking context with a higher z-index than its parent stacking context. You should place this element as a child of <body> whenever possible.