When I double click on a widget in the “My Widgets” sidebar panel, the widget opens in a new window by default. I wish it would open in a sidebar panel instead. Or please make it configurable.
Subject: based on user feedback, we changed the default action to open in new window
to open a widget in the sidebar, right-click on the widget in the My Widgets side panel and select ‘Open in - Sidebar Panel’
You can also set the default for a specific widget to always open in the sidebar on startup.
right-click on the widget in the My Widgets panel and select ‘Component properties’ and check the Contribute to Sidebar on startup’ option
Subject: Well, my user feedback is to change it back to open in the sidebar 
So I suggest You let users change this setting per widget.
Subject: Let me emphasize that
Opening them in the sidebar is the whole point of using widgets. If I’d like to open a DB view or a website in a new window I’d use a regular bookmark* or my browser. Widgets are there to be opened in the sidebar (or to be used for live text)
*If that was possible. I’ve seen numerous wished to be able to open bookmarks in a new window.
Subject: When you create a widgets YOU can pick the default actions
The creator of the widget can set the default action. In Notes 801, unfortunately, you can’t edit a widget once you build it. we want to fix that.
Subject: This doesn’t work
I just configured a new widget from a frameset and set these options:
Double clicking it in My Widgets still opens it in a new window.
Subject: Not supported
The double click action on a widget is coded to always open in a new window. It is not linked to the default open option chosen for actions created with the widget.
In the future we will let the user choose which open option they want to use. User would double click on the widget and a dialog would ask the user what they want the default to be. We would also allow editing of this preference.
Subject: Thank you.