Mouse motion event handler

def OnMouseMotion(self, event):
        """Mouse motion event handler"""

        grid = self.grid

        pos_x, pos_y = grid.CalcUnscrolledPosition(event.GetPosition())

        row = grid.YToRow(pos_y)
        col = grid.XToCol(pos_x)
        tab = grid.current_table

        key = row, col, tab

        merge_area = self.grid.code_array.cell_attributes[key]["merge_area"]
        if merge_area is not None:
            top, left, bottom, right = merge_area
            row, col = top, left

        grid.actions.on_mouse_over((row, col, tab))

        event.Skip()