Window.focusable

Function/Meaning
Whether focus can be acquired
Type
Property of the Window class (Read/Write)
Description
Represents whether focus can be acquired. You can also set this value.
If set to false, focus cannot be acquired, meaning the window will not become active. As a side effect, operations such as moving the window by grabbing the title bar, resizing the window, or closing the window by pressing the "x" button will also be disabled.
If you want to receive keyboard input, you can use the Window.trapKey property.
Normally, this is used for implementing windows that are displayed in the foreground but do not gain focus themselves, such as popup menus.
In the current version, the settings for this property may be lost when the window goes full screen or returns from full screen.
Reference
Window.trapKey
Window.onPopupHide