Open With Portal

Dialog to allow apps to open a file/URI with another app.

Goals / use cases

User opens a link or file type for the first time, and needs to give permission for it to be opened with another app
User wants to open a file or link with an app that isn't the default handler
- Example: open an image in an editor, from an image viewer
User opens a file / link type for which the default handler has been uninstalled
User wants to find out which apps are able to handle a particular file or link type
Optimise for around one to six apps available to open with
Inform the user if there are no installed apps capable of opening the file/link type
Allow the user to install more apps that are able to handle the file/link type

User wants to open a file or link with an app that doesn't know it can handle that file or link

Should default handlers be system-wide or per-app?

Probably fine to go with per-app. There will likely be cases where people want to specify it at this level.

Allow users to choose the default handler, or stop asking after they make the same choice three times?

Asking repeatedly could be annoying. Asking "always use this app" can be stress-inducing. This could be mitigated by explaining how the choice can be changed.

Do we need a place in Settings to undo or change the default?

You could potentially have a case where the open with dialog is shown the first time someone opens a file/link type (because there is no default set), but the app doesn't provide a way to force the open with option to be shown again.