Problem:

I'd like to hide columns for certain (non-working) hours in the TimelineView. How can I accomplish this?

Solution:

You can implement a custom time scale. It enables you to hide unneeded time periods.
A custom time scale class is inherited from the TimeScale class, overriding methods for the DateTime data handling and formatting.
You should override the following properties and methods:
SortingWeight - used to compare time scales;
Floor - specifies column boundaries;
HasNextDate - checks whether the move to the next date is allowed;
GetNextDate - navigates to the next date;
DefaultDisplayFormat - specifies the format for the column header caption;
DefaultMenuCaption - specifies the caption for the context menu item which enables this time scale;
FormatCaption - returns a string to be displayed as a column header caption.

To ensure a proper alignment of an upper (Day) scale, create a descendant with the Floor method overridden. Add this descendant to the scales collection in place of the default TimeScaleDay scale.