Popup is a base [Control] used to show dialogs and popups. It's a subwindow and modal by default (see [Control]) and has helpers for custom popup behavior. All popup methods ensure correct placement within the viewport.
Popup (show the control in modal form) in the center of the screen relative to its current canvas transform, at the current size, or at a size determined by [code]size[/code].
Popup (show the control in modal form) in the center of the screen relative to the current canvas transform, clamping the size to [code]size[/code], then ensuring the popup is no larger than the viewport size multiplied by [code]fallback_ratio[/code].
Popup (show the control in modal form) in the center of the screen relative to the current canvas transform, ensuring the size is never smaller than [code]minsize[/code].
If [code]true[/code], the popup will not be hidden when a click event occurs outside of it, or when it receives the [code]ui_cancel[/code] action event.
[b]Note:[/b] Enabling this property doesn't affect the Close or Cancel buttons' behavior in dialogs that inherit from this class. As a workaround, you can use [method WindowDialog.get_close_button] or [method ConfirmationDialog.get_cancel] and hide the buttons in question by setting their [member CanvasItem.visible] property to [code]false[/code].
Emitted when a popup is about to be shown. This is often used in [PopupMenu] to clear the list of options then create a new one according to the current context.
