Adding a pin to a collection is not obvious - need visual confirmation of this action

[BrightRaven]

Functionally, selecting a collection from the dropdown on a pin modal successfully adds that pin to that collection. However, there is no visual indicator to show this has happened. Users are going to be frustrated by this.

Suggestions for possible fixes:

• add a popup check box animation
• add an OK button instead of using the dropdown only (will also avoid inadvertently adding pins to collections that were unintended due to fat fingering the dropdown or misclicking)
• add a message that checks whether or not a pin already belongs to a collection and informs the user that the pin already exists there (do not allow user to try to add the pin again)