This page was written as a repsonse to a query on the Google Visualizations forum - https://groups.google.com/forum/#!topic/google-visualization-api/OZxw-KytWMo

I was hoping that by adding a new entry in the Data Table such as [ 'anything', '', new Date(0,0,0,19,0,0), new Date(0,0,0,23,59,0) ], creating a Data View from the Data Table and hiding the last entry using:

var dataView = new google.visualization.DataView(dataTable);
lastRow = dataView.getNumberOfRows() - 1;
dataView.hideRows([lastRow]);

that the draw method would draw the timeline including the the hidden entry timings but not drawing the row, of course, it doesn't work like that!

The best method I could come up with was adding a 1 second event to the end of the day of one of the existing events, a bit kludgy but it sort of produces the effect. The data I used was

[ 'Petunia Room', '', new Date(0,0,0,23,59,58), new Date(0,0,0,23,59,59) ]