This menu is from the embedded CurrencyEdit control in the cell. If you do not want to see it (or if you want to modify it), you can handle the TableControlCurrentCellControlGotFocus event. Here is code that will simply hide this menu to avoid these problems.
private void gridGroupingControl1_TableControlCurrentCellControlGotFocus(object sender, GridTableControlControlEventArgs e)
{
if(e.Inner.Control is GridCurrencyTextBox )
{
if(e.Inner.Control.ContextMenu.MenuItems.Count > 0)
e.Inner.Control.ContextMenu = new ContextMenu();
}
}