Question
Change the height of the grid column headers?
Resolution
In order to control the height of a cell (header or not) you must set the MinHeight property of the corresponding CellLayout.
You are free to have a unique CellLayout per cell (this is not likely what you need but it is possible).
To have different heights on the Header-cell and the cells under it, you must change the CellLayout for the header cell in runtime;
aGridColumn.ColumnCell.Layout=Grid.CellLayouts.GetFromName(“MyOtherCellLayoutWithAnotherMinHeight”);