In order to format the Ticks in a suitable way (0-300) we need to create a custom TickInterval and format it to return the total seconds difference between the current date and the start date. Hence, we need to preserve the start date somewhere so we can have it in the FormatValue method for the date difference extraction. This means, however, that the custom TickInterval should not be used as a shared resource between RadGanttViews, because the start date will be unreliable.
In order to display 0 - 300 time ruler range we need to change the RadGanttView.VisibleRange to 300 seconds.
To show each second in reasonable pixels we can modify the RadGanttView.PixelLength to something like 00:00:00.010.
Please find attached a sample project demonstrating this approach.
Hopefully this helps and is suitable for your scenario.
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