How to paint inactive rows in DataGridViewComboBox column?

Question

I can easily paint items in DataGridViewComboBox dropdown list. But I can't figure out how to paint inactive cells in the same column.

I've seen, studied and tried numberous examples for classical ComboBox, but I don't understand all aspects of DataGridViewComboBox.

Currently I have DataGridViewCustomPaintComboBox class derived from DataGridViewComboBox. What is the minimum set of overrides to supply? Can you point me in right direction?

Answer 1

The required minimum to paint inactive cells without the focus seems to be CellTemplate assignment and Paint() override:

public class DataGridViewCustomPaintComboBox : DataGridViewComboBoxColumn
{

    public DataGridViewCustomPaintComboBox()
    {
        base.New();
        CellTemplate = new DataGridViewCustomPaintComboBoxCell();
    }

}

public class DataGridViewCustomPaintComboBoxCell : DataGridViewComboBoxCell
{

    protected override void Paint(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, int rowIndex, DataGridViewElementStates elementState, object value, object formattedValue, string errorText, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts)
    {
        // modify received arguments here
        base.Paint(...); // paint default parts (see paintParts argument)
        // add any custom painting here

    }

}