Column size event handler

def OnColSize(self, event):
        """Column size event handler"""

        col = event.GetRowOrCol()
        tab = self.grid.current_table
        colsize = self.grid.GetColSize(col) / self.grid.grid_renderer.zoom

        # Detect for resizing group of cols
        cols = self.grid.GetSelectedCols()
        if len(cols) == 0:
            cols = [col, ]

        # Detect for selection of rows spanning all columns
        selection = self.grid.selection
        num_rows = self.grid.code_array.shape[0]-1
        for box in zip(selection.block_tl, selection.block_br):
            top_row = box[0][0]
            bottom_row = box[1][0]
            if top_row == 0 and bottom_row == num_rows:
                cols += range(box[0][1], box[1][1]+1)

        # All column resizing is undone in one click
        with undo.group(_("Resize Columns")):
            for col in cols:
                self.grid.code_array.set_col_width(col, tab, colsize)
                zoomed_colsize = colsize * self.grid.grid_renderer.zoom
                self.grid.SetColSize(col, zoomed_colsize)

        # Mark content as changed
        post_command_event(self.grid.main_window, self.grid.ContentChangedMsg)

        event.Skip()
        self.grid.ForceRefresh()