[Digit-Al]

I spent years designing interfaces for Windows Forms applications. There is no neccessity for sharing to be a dialog - it should be a wizard; and could even open in a new tab in a web application. Then the user can cancel either by pressing the cancel button (which would close the tab) or by just closing the tab. Selecting who to add, or adding a new person then just become pages in the wizard.

[quantadev]

Yeah everything theoretically could be done without dialogs, but the beauty of dialogs is that they can keep you from losing your place in what you're doing "behind" them, before they opened. Modal dialogs are less disorienting to users than just taking to some other "page", because they can tell what they're currently working on is still there behind the dialog.