Spreadsheet View

I can view a Model in spreadsheet-like form: That is, with Properties as the columns and Things as the rows.

I can change the width of a column in Spreadsheet View: This should be drag-and-drop on the column edge, as as in any ordinary spreadsheet.

I can create a Thing from Spreadsheet View: This looks like simply adding a new row at the bottom.

I can rearrange the columns in Spreadsheet View: I can drag a column header to move a column around.

I can sort Spreadsheet View on a column: Ideally, this is a little v/^ selector that appears when you hover in the column header, but make sure it works for small screens.

I can Sum a column in Spreadsheet View:

I can view a Model in spreadsheet-like form: That is, with Properties as the columns and Things as the rows.