I've test this problem and use following code for diagnostics (before tests I've hide some columns and reoder columns):
[c#]
protected override bool OnMouseClick(FlyGridViewPort port, NodeBase node, int col, int x, int y, int count, MouseButtons button)
{
Debug.WriteLine("Clicked Column is " + this.Columns.VisibleColumns[col].Caption);
base.OnMouseClick(port, node, col, x, y, count, button)
}
My tests is show that all works fine - columns recognized correctly.