master_selector.append_column_editable(_("Left"), exp_cols.left);
master_selector.append_column_editable(_("Right"), exp_cols.right);
master_selector.get_column(0)->set_min_width(100);
master_selector.append_column_editable(_("Left"), exp_cols.left);
master_selector.append_column_editable(_("Right"), exp_cols.right);
master_selector.get_column(0)->set_min_width(100);