HTML Widgets; widget.UI.Grid; Hidden row state incorrect after sorting column

Rows in a HTML Widget Grid can have a 'hidden' property which, when set to 'true', causes the row to be hidden and a special bar to appear below the grid indicating that there are hidden rows.

If this bar is clicked, hidden rows are then shown (and hidden again if it is clicked a second time).

However, if the bar was clicked to show hidden rows and then the "Sort" button at the top of a grid column was clicked, the rows were re-hidden and the message below the grid was then incorrect.

Sorting grid columns now retains the hidden state of grid rows.