Using a Keyboard Equivalent to Close a Subview

One of the Newton 2.x OS Q&As
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This document was exported on 7/23/97.

NEW: Using a Keyboard Equivalent to Close a Subview (5/12/97)

Q: In my application, I have a linked subview that is linked to a floater view. If I open that linked subview, then use a key command to close the view (on current devices, command-W), my application closes instead of the floater. How do I make the floater respond to a "close" key command?

A: There is a very subtle implementation detail of key-closing a view that is causing your problem. If you close a view using the keyboard, the following algorithm is used.

The children of each view, starting at the root view, are searched in reverse order for a close box.

The order of your base view's children can affect which view is first closed. If your close box or status bar child is after the linked layout child, then your application will be closed instead of the linked layout. If your close box or status bar child is before the linked layout child, then the linked layout will be closed first.

You can override this behavior by adding a _DoCloseButton method to your application's base view. The _DoCloseButton method is called when a keyboard equivalent is used to close a view. This method takes no arguments and must return true if you handled the close, or return nil to let the system continue to search for a close box in other applications.

Alternately, instead of creating your child as a linked subview, you could create it using the global function BuildContext. This guarantees that it will be searched for a close box before your application is searched.