Alt+Drag should Move the frame(s) to the new position. If the frame to wich it's being moved has something on it, it gets replaced. It should popup a warning saying there are stuff on the movedon frames already, to confirm the action, with an option to not warn again.

Ctrl+Click (not Drag) should select all the frames clicked, like in the old icon editor.
Shift+Click (not Drag) should select all frames in the scope, like in the old icon editor.