Requests a star-width column to calculate its ActualWidth.
void CalculateStarWidth(double availableWidth, double totalStars)
The available width to be shared by star-width columns.
The sum of the star units of all columns.
This method may be called multiple times during a layout pass; the width calculated by this method should not be comitted to ActualWidth until CommitActualWidth() is called. This method should update the value of the StarWidthWasConstrained property.